Fix Warnings on Launch (#1745)

* fix warnings on launch

* optimize png files

stuff/config/qss/Default/less/layouts/palette.less

@@ -22,7 +22,6 @@
 }
 
 #StyleEditorTabBar {
-  &:extend(.tab-container all);
   &::tab {
     &:extend(.tab-flat all);
   }
@@ -137,7 +136,6 @@ PaletteViewer {
 }
 
 #PaletteTabBar {
-  &:extend(.tab-container all);
   &::tab {
     &:extend(.tab-flat all);
   }

toonz/sources/include/toonzqt/styleeditor.h

@@ -738,6 +738,7 @@ protected slots:
 
 private:
   QFrame *createBottomWidget();
+  QFrame *createVectorPage();
   void updateTabBar();
 
   void copyEditedStyleToPalette(bool isDragging);