cf4778df74
On the Windows platform we get an initial bright white flash during startup, before we start drawing on our canvas. This PR changes that initial color to a mid-grey that is much less noticeable. After this initial fill is done we then clear the background brush so Windows will not use it later and slow down resizing by adding extra WM_PAINT messages and fills. Pull Request: https://projects.blender.org/blender/blender/pulls/137488