Решил изучать Java, установил Intellij IDEA. Когда начал с JavaFX, то при запуске приложения выдаёт много ошибок типа:
(java:14913): Gtk-WARNING **: 14:47:10.977: Theme parsing error: gtk.css:1:1: Expected a valid selector
(java:14913): Gtk-WARNING **: 14:47:11.002: Theme parsing error: gtk.css:238:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.003: Theme parsing error: gtk.css:244:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.003: Theme parsing error: gtk.css:251:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:296:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:305:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:314:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:323:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.005: Theme parsing error: gtk.css:361:54: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.005: Theme parsing error: gtk.css:366:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.006: Theme parsing error: gtk.css:482:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.007: Theme parsing error: gtk.css:500:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.007: Theme parsing error: gtk.css:516:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.008: Theme parsing error: gtk.css:532:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.008: Theme parsing error: gtk.css:553:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.009: Theme parsing error: gtk.css:608:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.009: Theme parsing error: gtk.css:621:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:633:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:645:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:654:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:665:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:675:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:688:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.017: Theme parsing error: gtk.css:699:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.017: Theme parsing error: gtk.css:708:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.018: Theme parsing error: gtk.css:728:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.018: Theme parsing error: gtk.css:738:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.019: Theme parsing error: gtk.css:759:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.019: Theme parsing error: gtk.css:803:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.020: Theme parsing error: gtk.css:819:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.020: Theme parsing error: gtk.css:835:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.021: Theme parsing error: gtk.css:851:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.021: Theme parsing error: gtk.css:872:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.027: Theme parsing error: gtk.css:893:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:903:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:916:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:927:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.029: Theme parsing error: gtk.css:936:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.031: Theme parsing error: gtk.css:977:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.032: Theme parsing error: gtk.css:991:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.033: Theme parsing error: gtk.css:1005:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1019:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1038:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1059:71: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1069:73: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1082:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1093:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1102:73: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.036: Theme parsing error: gtk.css:1192:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1206:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1214:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1220:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.038: Theme parsing error: gtk.css:1228:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.040: Theme parsing error: gtk.css:1541:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.047: Theme parsing error: gtk.css:1550:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1559:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1568:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1576:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.049: Theme parsing error: gtk.css:1678:24: Not a valid image
(java:14913): Gtk-WARNING **: 14:47:11.050: Theme parsing error: gtk.css:1713:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.050: Theme parsing error: gtk.css:1731:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1748:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1765:64: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1787:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.053: Theme parsing error: gtk.css:1840:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1852:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1864:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1877:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2667:54: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2686:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2693:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2724:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2733:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2743:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.061: Theme parsing error: gtk.css:2848:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.061: Theme parsing error: gtk.css:2859:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2871:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2886:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2896:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2906:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.063: Theme parsing error: gtk.css:2916:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.063: Theme parsing error: gtk.css:2925:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3126:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3135:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3143:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3154:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3165:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3174:71: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3183:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.070: Theme parsing error: gtk.css:3191:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.071: Theme parsing error: gtk.css:3371:47: Missing closing bracket for :not()
(java:14913): Gtk-WARNING **: 14:47:11.072: Theme parsing error: gtk.css:3574:55: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.073: Theme parsing error: gtk.css:3644:14: Invalid name of pseudo-class
(java:14913): Gtk-WARNING **: 14:47:11.073: Theme parsing error: gtk.css:3701:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4215:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4223:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4232:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.087: Theme parsing error: gtk.css:4341:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.088: Theme parsing error: gtk.css:4477:8: not a number
(java:14913): Gtk-WARNING **: 14:47:11.088: Theme parsing error: gtk.css:4477:17: Using Pango syntax for the font: style property is deprecated; please use CSS syntax
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4672:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4680:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4688:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4695:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4703:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4711:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4718:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4726:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4734:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.002: Theme parsing error: gtk.css:238:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.003: Theme parsing error: gtk.css:244:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.003: Theme parsing error: gtk.css:251:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:296:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:305:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:314:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.004: Theme parsing error: gtk.css:323:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.005: Theme parsing error: gtk.css:361:54: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.005: Theme parsing error: gtk.css:366:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.006: Theme parsing error: gtk.css:482:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.007: Theme parsing error: gtk.css:500:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.007: Theme parsing error: gtk.css:516:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.008: Theme parsing error: gtk.css:532:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.008: Theme parsing error: gtk.css:553:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.009: Theme parsing error: gtk.css:608:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.009: Theme parsing error: gtk.css:621:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:633:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:645:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.011: Theme parsing error: gtk.css:654:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:665:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:675:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.012: Theme parsing error: gtk.css:688:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.017: Theme parsing error: gtk.css:699:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.017: Theme parsing error: gtk.css:708:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.018: Theme parsing error: gtk.css:728:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.018: Theme parsing error: gtk.css:738:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.019: Theme parsing error: gtk.css:759:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.019: Theme parsing error: gtk.css:803:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.020: Theme parsing error: gtk.css:819:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.020: Theme parsing error: gtk.css:835:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.021: Theme parsing error: gtk.css:851:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.021: Theme parsing error: gtk.css:872:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.027: Theme parsing error: gtk.css:893:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:903:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:916:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.028: Theme parsing error: gtk.css:927:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.029: Theme parsing error: gtk.css:936:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.031: Theme parsing error: gtk.css:977:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.032: Theme parsing error: gtk.css:991:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.033: Theme parsing error: gtk.css:1005:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1019:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1038:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.034: Theme parsing error: gtk.css:1059:71: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1069:73: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1082:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1093:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.035: Theme parsing error: gtk.css:1102:73: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.036: Theme parsing error: gtk.css:1192:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1206:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1214:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.037: Theme parsing error: gtk.css:1220:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.038: Theme parsing error: gtk.css:1228:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.040: Theme parsing error: gtk.css:1541:68: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.047: Theme parsing error: gtk.css:1550:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1559:67: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1568:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.048: Theme parsing error: gtk.css:1576:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.049: Theme parsing error: gtk.css:1678:24: Not a valid image
(java:14913): Gtk-WARNING **: 14:47:11.050: Theme parsing error: gtk.css:1713:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.050: Theme parsing error: gtk.css:1731:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1748:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1765:64: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.051: Theme parsing error: gtk.css:1787:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.053: Theme parsing error: gtk.css:1840:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1852:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1864:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.054: Theme parsing error: gtk.css:1877:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2667:54: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2686:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.059: Theme parsing error: gtk.css:2693:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2724:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2733:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.060: Theme parsing error: gtk.css:2743:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.061: Theme parsing error: gtk.css:2848:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.061: Theme parsing error: gtk.css:2859:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2871:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2886:70: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2896:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.062: Theme parsing error: gtk.css:2906:69: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.063: Theme parsing error: gtk.css:2916:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.063: Theme parsing error: gtk.css:2925:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3126:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3135:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.068: Theme parsing error: gtk.css:3143:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3154:72: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3165:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3174:71: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.069: Theme parsing error: gtk.css:3183:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.070: Theme parsing error: gtk.css:3191:74: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.071: Theme parsing error: gtk.css:3371:47: Missing closing bracket for :not()
(java:14913): Gtk-WARNING **: 14:47:11.072: Theme parsing error: gtk.css:3574:55: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.073: Theme parsing error: gtk.css:3644:14: Invalid name of pseudo-class
(java:14913): Gtk-WARNING **: 14:47:11.073: Theme parsing error: gtk.css:3701:56: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4215:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4223:60: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.083: Theme parsing error: gtk.css:4232:62: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.087: Theme parsing error: gtk.css:4341:58: Using one color stop with linear-gradient() is deprecated.
(java:14913): Gtk-WARNING **: 14:47:11.088: Theme parsing error: gtk.css:4477:8: not a number
(java:14913): Gtk-WARNING **: 14:47:11.088: Theme parsing error: gtk.css:4477:17: Using Pango syntax for the font: style property is deprecated; please use CSS syntax
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4672:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4680:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.089: Theme parsing error: gtk.css:4688:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4695:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4703:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4711:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4718:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4726:14: negative values are not allowed.
(java:14913): Gtk-WARNING **: 14:47:11.090: Theme parsing error: gtk.css:4734:14: negative values are not allowed.
P.S. После запуска в Intellij IDEA программы на выполнение, программа выполняется, но размер окна не такой, как я прописал в проге. Думаю, что это тоже связано с css.