Always on top: Add an option to make the window transparent

[alias-paj]

Description of the new feature / enhancement

A window set to "always on top" does not only get a coloured border but does change its overall transparency. This would allow to see through the window.
An additional slider in the settings would allow adjust the transparency of the window.

Scenario when this would be used?

Whenever I need have some data in view, a list of things, dimensions of an object, price tags, to-do lists, images, and I want to use the complete screen.
As an example:
I do have a To-Do list a client send, and I need to make some changes, this includes some drawings, some research on the internet, some manipulation of data. I do need to change a lot of programs to archive the task, but I need the To-Do list always on top, however sometimes it blocks the view (surfing the web).

Supporting information

No response

[ethanfangg]

/dup #1084

[microsoft-github-policy-service]

Hi! We've identified this issue as a duplicate of another one that already exists on this Issue Tracker. This specific instance is being closed in favor of tracking the concern over on the referenced thread. Thanks for your report!