These images are created by the “DockableMovingImageFactory”. Currently the only way to change this factory is to access (or override, or wrap) the DockTheme you use and either call “setMovingImageFactory” or override “getMovingImageFactory”.
If you use the Core-project this is easily done as you have to create the DockTheme anyways.
If you use the Common-project you should create some wrapper class and call “ThemeFactory.put(…)” with the keys specified in ThemeMap and your factory. Something like:
for( int i = 0; i < map.size(); i++ ){
map.put( map.getKey(i), new MyFactory( map.getFactory( i ) ));
}```
(this will get easier in version 1.1.0, but that is yet far away).