FileBrowserSheet not responding

I'm having some issues with FileBrowserSheet.
When I browse folder on the network, it is quite slow.
Sometimes the file browser does not react at all...
So I want to set the cursour to Cursor.WAIT to show the user that the sheet is working.
I tried to set my own skin on the FileBrowserSheet so I did this :

• I subclassed org.apache.pivot.wtk.FileBrowserSheet
• I subclassed org.apache.pivot.wtk.skin.terra.TerraSheetSkin and created my skin
• In the constructor, I call the setSkin method but I get the following error "Skin is already installed". It is because it calls the installThemeSkin(FileBrowserSheet.class) in the org.apache.pivot.wtk.FileBrowserSheet and once the skin is installed, I can't set another one.