Multiple contexts/windows affecting each other's viewport/input/window coordinates

Dear ImGui 1.82 (18200)
sizeof(size_t): 8, sizeof(ImDrawIdx): 4, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: _WIN32
define: _WIN64
define: _MSC_VER=1924
define: _MSVC_LANG=201402
define: IMGUI_HAS_VIEWPORT
define: IMGUI_HAS_DOCK
io.BackendPlatformName: NULL
io.BackendRendererName: NULL
io.ConfigFlags: 0x00000040
DockingEnable
io.ConfigViewportsNoDecoration
io.ConfigInputTextCursorBlink
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x00000000
io.Fonts: 1 fonts, Flags: 0x00000000, TexSize: 512,64
io.DisplaySize: 1100.00,700.00
io.DisplayFramebufferScale: 1.00,1.00
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00

Back-end/Renderer/Compiler/OS

Operating System: Windows 10.0.19044

My Issue/Question:

Hi all,

I'm using imgui via the pyimgui-wheels Python module (https://github.com/pyimgui/pyimgui) but since that repo is not very active and I believe this issue is imgui itself and not in the python wrapper (the python module just provides calls the imgui c++ library) I am posting here. I am also not sure whether my problem is due to a bug or a mistake I am making, but I am starting to feel it is a bug.

The problem is as follows: I have two glfw windows, A and B, with each their own imgui context. Window A is made first, then the imgui context is set up for it, then window B is made and the imgui context for it is set up, using a font atlas pointer grabbed from imgui context A. When glfw window A is resized, imgui windows in window B move. It seems that the (imgui?) viewport in window B is also resized when I resize glfw window A.

Using the imgui metrics window I found out that both contexts have one imgui viewport each. These viewports are both called 'Viewport #0' and have the same ID (0x11111111), parent (0x00000000) and Window ("N/A") but they do have a different size: (1100, 700) for (glfw) window A, and (600, 700) for window B, which is the size I set for the glfw window upon making them. When I change the size of glfw window A, the viewport of imgui context A changes in size accordingly while that of context B is not affected. However, when I make viewport A smaller in size than viewport B, imgui graphics in window B are clipped to the size of viewport A. Moreover, when I change the height of glfw window B, the imgui cursor position if offset w.r.t the actual on screen cursor position. Meanwhile in window A everything is behaving as it should.

After making the glfw windows, I set imgui up like this:

[make glfw_window_a]
glfw.make_window_current(glfwwindow_a)
imgui_context_a = imgui.create_context()
imgui_impl_a= GlfwRenderer(glfwwindow_a)
[set glfwwindow_a callbacks, etc., including glfw.set_window_size_callback(...), not sure if relevant]

[make glfw_window_b]
glfw.make_window_current(glfwwindow_b)
imgui_context_b = imgui.create_context(imgui_impl_a.io.fonts)
imgui_impl_b = GlfwRenderer(glfw_window_b)
[set glfwwindow_b callbacks, etc., including glfw.set_window_size_callback(...), not sure if relevant]

Then in the main loop:

imgui.set_current_context(imgui_context_a)
imgui.new_frame()
[gui for window a, and other app-specific things]
imgui.render()
imgui_impl_a.render(imgui.get_draw_data())

imgui.set_current_context(imgui_context_b)
imgui_impl_b.refresh_font_texture()
imgui.new_frame()
[gui for window b, and other app-specific things]
imgui.render()
imgui_impl_b.render(imgui.get_draw_data())

Standalone, minimal, complete and verifiable example:

I'm hoping the above description is sufficient to ring a bell with someone, if not I will set up a minimal example.