Brief black background when resizing a window

[Igor Bukanov]

Hi,

In a debug build of Chromium on a laptop with a throttled-down CPU on Windows 11 Chromium on startup shows briefly a white background before the UI appears.  But then when I resize the window like via clicking the maximize button or via dragging the border the extended area of the window briefly shows the black color, not white.  Where does this black color comes from? 

I do not think that this is an artifact of the driver or OS as the black color with a sufficiently throttled down CPU stays long enough to read the word Restore and the close button cross rendered in white on top of that black near the right edge of the window. This word and the button in my case I suppose comes from from the Restore Session dialog.  

And also where exactly the initial white is defined? Initially I though that it comes from one of view::Background implementations. But then I commented out the background painting in views::view::OnPain() and that still showed the white background on startup even if some of the elements of UI got blue background.

Regards, Igor 

[Bruce Dawson]

There are various bugs that have tracked variations on this issue over the years - some fixed, others not.

crbug.com/590448 is one of the more detailed and well analyze

crbug.com/1212891 is a much more recent report which, curiously enough, is on Linux

crbug.com/1257540 is another Windows bug report about this type of issue. A fix was landed, but then reverted.

crbug.com/853986 is a cross-platform report of this issue

I think that window initialization is extremely complicated as we want it to happen quickly but also don't want to display intermediate results. And, window management (in Windows at least) has changed dramatically over the years.

I would recommend commenting on crbug.com/590448 as that has probably the best analysis.

BTW, I found these bugs by searching crbug.com for black flash.