[FR] Make window selection more prominent

[tmnrdhf]

Problem or Need

Currently the selected window in dock preview and window switcher is barely visible. There is just a very subtle colored layer (which also weirdly changes unless you adjust the settings) and the window slightly increases in size. (I don't even want to imagine how it is visually impaired people.)

Proposed Solution

Could the selected window be made more visible? I think AltTab does it very well, see example here.

• [x] I have reviewed the open issues to ensure this is not a duplicate feature request

[illavoluntas]

Looks like a duplicate of #260, reopened it now