LTreeViewItem: implemented getItemHeight/Width as callbacks
LuceO: fixed pop'ing too much when passing a LColour
LuceO: LuceO: Colours: set default to TransparentWhite when not found by string
removed transparentBlack and transparentWhite from list of Colours as they are not provided by findColourForName
LTreeViewItem: pass selected state to callback
added: LImageButton