Viewports: Fix window having incorrect size after it is uncollapsed

[rokups]

Issue manifests on linux when window is in it's own viewport.

Why it happened

Event sets PlatformRequestResize = true which causes this line to execute and save size of collapsed window as full size.

SDL backend does not send window resize event when SDL_SetWindowSize() is called and everything works as expected.

On windows glfw still sends this event, but event is sent during glfwSetWindowSize() call which is invoked from here. Due to lucky accident PlatformRequestSize is cleared soon after imgui requests setting window size. It works on windows by chance.

On linux event is queued and sent to application on next frame during glfwPollEvents(). Then imgui gets a chance to react on PlatformRequestSize flag and save wrong window size.

[ocornut]

Thanks Rokas!
The only change I would do is to move the bool inside the ImGuiViewportDataGlfw structure, so it would work if multiple viewports are resized in the same frame (which is bounds to happen if resized from code).

[rokups]

Done 👍

[ocornut]

Merged with subsequent fixes for Windows (a4af3cc) because we don't always receive a size event after glfwSetWindowSize().

I have a feeling we will have to come back to this at some point, and making the change already is the best way for us to notice other issues later.

Thanks @rokups !