Unnecessary re-render when moving windows in eframe

[Detector-I]

Describe the bug

I don't know why but eframe will render gui in any mouse event on the program, even outside of the gui itself, like when moving the window by dragging titlebar...
I don't think that this behavior should be the default... because there is no need to render gui itself when just moving the windows...
other gui library like imgui (using example backends) wont re-render on this kind of events

To Reproduce

Steps to reproduce the behavior:

1. Create any program with eframe
2. Try to moving it by mouse (dragging windows titlebar)
3. Check the CPU & GPU usage...

Expected behavior

eframe shouldn't re-render the gui when user simply moving the program window itself (and there isn't any input or update to gui itself)

Screenshots

no input or update in gui itself, just moving program windows (really fast...)

Desktop (please complete the following information):

• OS: Windows 10

Additional context

The interesting thing is if we try to move the window using arrow key in keyboard using the option in windows menu (I can recall exact name of it) there is no re-render, because seems like eframe will render gui only on mouse events

[JosuGZ]

I don't think this is a bug. But it would be nice to have better behavior.

I think it should be possible to keep data from the previous frame to decide whether a redraw is needed or not. Components would save there a bounding box of the area they are interested in along with the type of event (enter, leave, move...). Before rendering, the library could check if the mouse is interacting with those areas.

[Detector-I]

@emilk thank you for fast respond.
I tested it but seems like it still re-render when moving window... there is something that im missing? (like I need to set an option or something?

[emilk]

Use RUST_LOG=debug and eframe will log what event caused the repaint ("Repaint caused by …"). You'll have to take it from here, because on my mac it works as intended.

[Detector-I]

Use RUST_LOG=debug and eframe will log what event caused the repaint ("Repaint caused by …"). You'll have to take it from here, because on my mac it works as intended.

thank you for the answer, I used $env:RUST_LOG="debug"; but still didn't get any debug output in my windows powershell...
I know its kind of outside of here but can you tell me how can I setup tracing?