If I would calculate the position of the cursor on the panel, you could maybe provide a sort of message function that takes the PANEL*, the cursor position on the panel and a flag covering the button state (none, click, rightclick). So when I write an on_click event for the entity/sprite/whatever, I would calculate the position on the panel (in panel coordinates!) and then execute the message function. Would this work? I guess you use as well a similar function in the engine that takes the mouse position and the button state and then you cycle through all visible panels!?

Do you think a nested panel-collection would be natively possible with target_map? If not, would you have fun to work on this?

Cheers, Christian