Watermark Image

I have already a image like watermark, Now I have two listbox and I want to add that picture like watermark but transparent, I want the picture over
both listbox but I want to see the data of the listbox

Best way is probably an attached overlay window, MBS Plugins has such a class (OverlayMBS) https://www.monkeybreadsoftware.net/class-overlaymbs.shtml

Actually, you can do this simply by putting a Canvas on top of it.
Draw your image in the canvas paint event.
Set the picture to be semi transparent using a mask or alpha channel.

As long as you don’t return true in the canvas mousedown, the listbox underneath seems to work fine.