SDL3: ImGui_ImplSDL3_UpdateMonitors expensive on macOS

[TheMode]

Version/Branch of Dear ImGui:

docking/fonts

Back-ends:

SDL3 + SDL_GPU

Compiler, OS:

macOS Clang 16

Full config/build information:

No response

Details:

Monitors are currently being constantly iterated over in ImGui_ImplSDL3_NewFrame.
On macOS, SDL_GetDisplayUsableBounds shows to be about ~90% of the NewFrame cost, around 3% of my entire app.

I may be wrong, but I assume that this could be replaced by SDL's display events e.g. SDL_EVENT_DISPLAY_ADDED/SDL_EVENT_DISPLAY_REMOVED/SDL_EVENT_WINDOW_DISPLAY_SCALE_CHANGED

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

No response

[ocornut]

This is caused by our fairly recent change: #8415 (comment)

Unfortunately there's no indicator on SDL front that work area may have changed so we started polling for this.
Will move this discussion to SDL3 repo, either the performance issue needs to be addressed either it would be good to have a signal for work area change.

[ocornut]

I have posted a new SDL issue libsdl-org/SDL#12785
And will work on reverting the change to limit the polling to Win32 platform for now.

[ocornut]

I have pushed b811c42 which should work-around this.