Crashed when using multi-viewport on the expand screen in windows 10

[ChivenZhang]

Version/Branch of Dear ImGui:

Version: 1.88#1
Branch: docking

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_SDL.cpp + imgui_impl_OpenGL3.cpp
Compiler: MSVC of Visual Studio 2019
Operating System: Windows 10

My Issue/Question:

Steps below:

• Create Dock Window
• Create Normal Window (imgui::begin, imgui::end)
• Move Dock Window to another expand screen in windows 10 (there are two expand screens in my pc)
• Then drag out the Normal Window from dock space
• And it crashed which need to kill the process

Screenshots/Video

NONE

Standalone, minimal, complete and verifiable example: (see #2261)

	const ImGuiViewport* viewport = ImGui::GetMainViewport();
	ImGui::SetNextWindowPos(viewport->WorkPos);
	ImGui::SetNextWindowSize(viewport->WorkSize);
	ImGui::SetNextWindowViewport(viewport->ID);
	ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
	ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
	ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
	ImGuiWindowFlags window_flags = ImGuiWindowFlags_MenuBar | ImGuiWindowFlags_NoDocking;
	window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
	window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoNavFocus;
	ImGui::Begin(m_Name.getValue().c_str(), nullptr, window_flags);
	ImGui::PopStyleVar(3);
	auto dockspace_id = ImGui::GetID(m_Name.getValue().c_str());
	ImGuiDockNodeFlags dockspace_flags = ImGuiDockNodeFlags_None;
	ImGui::DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags);
	ImGui::End();

[PathogenDavid]

I can't reproduce this, but your code snippet isn't totally self-contained either. Can you provide a stack trace of the crash? Do you experience this crash in the official examples?

[ChivenZhang]

I can't reproduce this, but your code snippet isn't totally self-contained either. Can you provide a stack trace of the crash? Do you experience this crash in the official examples?

I have tried official example [example_sdl_opengl3.cpp] in other computer, It works well except mine.
My own pc is 'Dell G15' which made by one screen integrated and an expand screen 'Dell G2422HS' which using gpu accelerate.
You can visit website below for more product infomation about the expand screen, i guess it caused by hardware.
https://www.dell.com/support/kbdoc/zh-cn/000131820/dell-amd-freesync-monitors-that-are-nvidia-g-sync-compatible?lang=en

[ChivenZhang]

I can't reproduce this, but your code snippet isn't totally self-contained either. Can you provide a stack trace of the crash? Do you experience this crash in the official examples?

I'll take you the stack trace after working.

[ChivenZhang]

I can't reproduce this, but your code snippet isn't totally self-contained either. Can you provide a stack trace of the crash? Do you experience this crash in the official examples?

The process was just block here and never step out when I tried to drag the normal window out of frame on the second screen.

Source Code:

Viewport Block:

Stack Trace:

[ocornut]

Hello, looks related to multi-viewports and has nothing to do with docking. Please check the other threads about problems on Windows with OpenGL eg #4468 and #4832.

Please also make sure you don’t have broken software like Nahimic installed #3321 #5354.

[ChivenZhang]

Hello, looks related to multi-viewports and has nothing to do with docking. Please check the other threads about problems on Windows with OpenGL eg #4468 and #4832.

Please also make sure you don’t have broken software like Nahimic installed #3321 #5354.

I am sure that I used a single thread for both opengl swapbuffer and imgui draw. Of course not using Nahimic software .etc.

[PathogenDavid]

Since the crash is happening in external code above the implementation of SDL_GL_SwapWindow this is probably being caused by something injected into your process or buggy drivers. If you right-click the call stack window and select "Show External Code" you can get more details.

It would also be helpful to see the list of modules loaded into the process during the crash. You can open the list under Debug > Windows > Modules (default shortcut is Ctrl+Alt+U.) You can copy+paste from that table into a GitHub Gist and share it here.

[ChivenZhang]

Umm, It's ok to develop my application without viewport feature. So I Just close this issure.