Flash stop receiving keyboards after Drag'n Drop, until I click the Flash again, or use Tab key... Weird problem

I have a puzzling problem with Flash.

Coding a game, like so 开发者_运维问答many others. Javascript and Flash both listen to keyboard events. Javascript redirects keys to Flash, like many others seem to do. It's working fine.

Then I created an inventory and items. Icons that can be dragged and dropped.

But if I drag and drop an item, suddenly, the keyboard events stop being triggered until I click once again on the Flash, on the html document, or until I enter "tab mode" by pressing tab! It's like the focus is nor on Flash, nor on Javascript. Although I guess the focus should somehow still be on Flash, otherwise how could it enter "tab mode"?

Do you have any insight what the problem might be? Thanks in advance.

PS: please tell me if my explanations are unclear.