A vertical offset on ubuntu when a panel is separated from the main window

[shi-yan]

Version/Branch of Dear ImGui:

f1bf642e8f9b2a2ecbe03de10743bd1e504cb3f8

Version: 1.82 WIP Branch: docking

Back-end/Renderer/Compiler/OS Tried both opengl3 and vulkan/ sdl, gcc-8 ubuntu 18.04 on nvidia / xwindows

Back-ends: imgui_impl_sdl.cpp, vulkan / opengl3 Compiler: gcc-8 Operating System: ubuntu 18.04

My Issue/Question:

I'm testing the docking branch with the official examples. I have tried both the vulkan backend and the opengl3 backend. I have noticed some issues.

One problem is that I noticed a mouse position offset, if the demo window is separated from the main window. The issue is kinda intermittent, because there was one time, after I dragged the main window around, somehow that fixed the offset issue.

It seems that the vertical offset equals the distance between to top boundary and the top border of my screen.

Screenshots/Video

Standalone, minimal, complete and verifiable example:

this is the same official demo, but it has a CMake file

testimgui.zip