@ustk Awesome, that looks like it'll work great, though I'm getting slight flashbacks to similar control-layering jankyness in Kontakt.
For anyone reading this later, the solution is to script a panel to have mouse interaction slider behavior, or to use an invisible slider for mouse interaction and the panel only for drawing.
You can change which image is loaded using ScriptPanel.loadImage, and update the drawing of the panel with Graphics.drawImage.
David's tutorial covers a lot of relevant stuff here