>The compositor has a frame to paint and it can't have to wait on applications.
This is the source of the visual artifacts this article is trying to prevent, however. Sure, you probably don't want to block resize for multiple seconds, but in general the compositor is very responsive. The app may not be. If you just let the window chrome resize as fast as you get, what do you do with the rest of the window? Leave it transparent? Draw a default black or white area? Both are very ugly and very noticeable in practice.
This is the part of the problem space I know the most about - for a number of years I owned window chrome on Windows (don't blame me for the 1px border and way-too-subtle shadows, but after being overruled by PM/design, yes, I was responsible for implementing them).
As far as custom decorations - that is a lost battle. Companies and apps want their special design language and will simply not build for your product/operating system/compositor/whatever if you don't give them that kind of support. Twitter and Facebook both want their specific shade of blue and their specific font. Adobe is....well, let's not talk about Adobe. Browser tabs in the title bar are a P0 requirement these days and anyone who doesn't support that will be laughed out of the room. Etc., etc.
This is the source of the visual artifacts this article is trying to prevent, however. Sure, you probably don't want to block resize for multiple seconds, but in general the compositor is very responsive. The app may not be. If you just let the window chrome resize as fast as you get, what do you do with the rest of the window? Leave it transparent? Draw a default black or white area? Both are very ugly and very noticeable in practice.
This is the part of the problem space I know the most about - for a number of years I owned window chrome on Windows (don't blame me for the 1px border and way-too-subtle shadows, but after being overruled by PM/design, yes, I was responsible for implementing them).
As far as custom decorations - that is a lost battle. Companies and apps want their special design language and will simply not build for your product/operating system/compositor/whatever if you don't give them that kind of support. Twitter and Facebook both want their specific shade of blue and their specific font. Adobe is....well, let's not talk about Adobe. Browser tabs in the title bar are a P0 requirement these days and anyone who doesn't support that will be laughed out of the room. Etc., etc.