window-actor: Only fall back to shadows if the window has a shape

[jaszhix]

This includes all of the windows I think we would want to have shadows, such as framed windows, GTK CSD windows, and chromium windows.

This removes shadows on windows such as Steam, which has artifacts because it initially maps its menus outside of the parent window causing it to lose focus, which makes the shadow border flicker between focused and unfocused while hovering over selections.

Ref #398

[clefebvre]

I see two issues with Steam and they're both visible in the video.

https://github.com/linuxmint/muffin/files/2771746/mint191_menu_glitch.mp4.zip

• The most visible issue is that both Steam itself and its menus act like windows with shadows, so when you open a menu in Steam, muffin thinks the main Steam window isn't focused anymore and draws a smaller shadow than before... this is fixed by this PR as it removes the shadow on the main window.

• Artifacts show in the top left corner of the screen. This is only partially fixed by this PR. Although the main window loses its shadows, some of the menus still generate shadows.

[jaszhix]

I think this could be fixed by doing a full revert of 9ce8125.

I can't spend any more energy on this, especially when I think shadows look stupid on CSD windows that are not intended to have any.

[clefebvre]

OK, just tested a revert of 9ce8125, it affects chrome/chromium but has no impact on steam and doesn't fix this bug.

I also checked steam under Marco and Metacity, both render shadows not only for Steam, but for its menus... and they both have the same issue as Muffin, i.e. they both suffer from https://github.com/linuxmint/muffin/files/2771746/mint191_menu_glitch.mp4.zip

[clefebvre]

I'm going to close this. I think since it affects all DEs, it's up to Steam to fix it. They should use proper menus really, not defocus their main windows like they're doing now.

[jaszhix]

I think it's still a Muffin issue. Steam does not create shadows for its menus, which means we're applying shadows to window types we shouldn't be. This is not a Steam bug because as far as they're concerned those window menus are not visible in other WMs while being mapped.

[jaszhix]

ValveSoftware/steam-for-linux#6