I'm hoping I can get away with communicating the issue I'm having clearly without posting a ton of source code. The source is all ASM and while most would understand it, it's still not their primary "thing."
I have a layered window which is working perfectly - up to the point of resizing it. The window is all per-pixel alpha. There are no transparent pixels. The borders and caption are opaque (255 alpha); the client area is something like 128 alpha or whatever I put it at. So no transparent pixels.
I have a function that handles redraws - it's actually geared toward rebuilding the frame for a new window size. GetWindowDC is called on the layered window. CreateCompatibleDC creates off of that DC. The bitmap is a DIB section. The bitmap is properly sent to UpdateLayeredWindow. Again, everything works perfectly as long as the window is not in active resize (border drag).
I have tried using DefWindowProc to handle border drags, as well as completely handling all aspects of that functionality myself. The results are the same: massive flicker but ONLY beyond the window boundaries that existed before border drag began, and then the window size does not ultimately change - sort of. The original window area remains displayed without issue. No flicker there. However if (for example) I'm dragging the right border to the right, everything right of the original window right edge flickers rapidly then vanishes. When I release the left mouse button, the display remains at the original size (the size the window was before dragging the border). I've verified the bitmap is correctly rebuilt to the new size. It seems like the DC for the layered window doesn't want to resize because the entire area of original window size is completely stable, but any new area appearing post-resize flickers then hides.
I've even tried removing the ws_ex_layered style before resizing the window in my manual handling (I've tried both MoveWindow and SetWindowPos) then resetting the ex style after SetWindowPos / MoveWindow but before dragging.
When I let DefWindowProc handle the updates, I got the exact same result. So indications are that something is wrong with my repainting. But I even whittled that process down (commenting out oodles of code for test) and just filled the bitmap with 0xFF0000FF (arbitrary test value, blue, full opacity) then jumped straight to UpdateLayeredWindow. Same result.
The bitmap used for UpdateLayeredWindow is deleted before calling the "rebuild" function and within the function that bitmap is recreated to the new size. I have verified the new size extensively - I can see the new bitmap as it high-speed flickers and it's all good. The DC is GetWindowDC from the layered window. The compatible DC creates off that DC. The bitmap is selected into the compatible DC, and that compatible DC is passed to UpdateLayeredWindow. If any of these things were off, I would never see the new bitmap displayed. It's there - it just flickers at high speed ONLY beyond the window bounds that existed before resize began. DefWindowProc yields the same results. Within that original area, my caption buttons slide off to the right as I drag the right border to the right, further verifying everything is good.
I'm at a loss. Any input would be welcome.
