ImGuiConfigFlags_ViewportsEnable apparently reseted after ImGui::NewFrame();

[LittleCoinCoin]

Version/Branch of Dear ImGui:

Version: 1.88
Branch: docking

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_glfw.cpp + imgui_impl_vulkan.cpp
Operating System: Win 10

My Issue/Question:
I doubt this is an ImGui bug otherwise I think there would be more people talking about it. So, this is probably my fault and I sincerely apologize for the bother.

I am trying to switch from a project that was not using multi-viewport to a project that is using multi-viewport.
I read this post and this thread.
I added the relevant config flag (ImGuiConfigFlags_ViewportsEnable) in the initialization part of my code before at the same place as in provided example for glfw and vulkan. (see screenshot 1).
As far as I can tell, the rest of my "initialization code" is also identical to the provided example for glfw and vulkan.
Then, according to my debug information, ImGuiConfigFlags_ViewportsEnable stays true until ImGui::NewFrame(); is called in my update loop (see screenshot 2 and 3).

As a result, multiviewport is never accessible at runtime.
Also, if I try to forcefully add the flag via the Demo Window, I can see the Demo Window jiterring, trying to deisplay the additional CheckBoxFlags() but ImGuiConfigFlags_ViewportsEnable is immediately set back to false.

Could anyone point out my mistake?

Thank you in advance!

Screenshots/Video

1. 
2. 
3. 

[ocornut]

It is disabled if not supported by both backends. The flag needs to be initially set at the time of initializing both backends.

[ocornut]

It is unclear from your code snippets where the backends are initialized.

[ocornut]

Apologies for one liners answers, I guess I shouldn’t be reading on my phone.

You can set a data write breakpoint in Visual Studio debugger, or step in ErrorCheckNewFrameSanityChecks() to find where the flag is being disabled, there are various possible reasons for the disabling.

[LittleCoinCoin]

Thank you very much for your reactivity and investment in every issues @ocornut. 🙏
I will investigate in this direction and report later.

[LittleCoinCoin]

Well, as expected this was entirely my fault: I simply had forgotten to update the backend code (imgui_impl_glfw.h/cpp + imgui_impl_vulkan.h/cpp) of the project since I was initially running a "non-multi-viewport". I'm ashamed... (I spent 4 hours yesterday rechecking everything and, everytime,I forgot the same step). Sorry to have polluted the issues for that.

Thank you again for putting me back on track! 🙇‍♂️