Widgets not redrawing...

I’ve got a multi-windows photon application, and very strangely, on the main window, all the widgets which I added after some point do not refresh correctly after being covered by another window, either from the program or from another application.

So basically I created this main window with a Ptraw and a few PtButtons which always update properly, and later on I added a few more, and those do not ! I tried to use PtFlush with no success.

Any idea on what the problem can be ?