Can egui be used to make transparent overlay addon program over a game?

[coderedart]

Apologies for the long question.
I am thinking of making a crossplatform overlay program for a game called guild wars 2. something similar to http://www.gw2taco.com/2015/01/feature-list.html which is windows only.

in terms of GUI, there's 2 requirements for doing this.

1. The main window needs to be transparent and stay on top with only the markers or whatever i draw on the painter device being visible over the game.
2. The main window must allow all the inputs to pass through like mouse cursor clicks/keyboard key presses etc.. except a file menu on top left which must open the menu/settings for the program when clicked

i guess in terms of Qt, i want to be able to set the widget attributes Qt::WA_TranslucentBackground for transparency and the window attributes Qt::WindowStaysOnTopHint to keep it ontop of game and Qt::WindowTransparentForInput to allow input to pass through and finally Qt::FramelessWindowHint so that there's no minimize/close buttons or titlebar as the overlay should not be able to move;

I just wanna know if this is possible in egui, as I really want want to use it over qt. the gui getting input from the socket/game shared memory, and drawing the routes/markers etc.. every frame seems like a job for immediate mode api.

[emilk]

egui_glium already supports transparent and non-decorated windows. Adding a always_on_top flag is easy.
Passing on input should probably be doable, but I'm not sure how (help wanted?).

[emilk]

I added always_on_top as an option in a7a36bd