Undocking interrupts drag with ConfigDockingAlwaysTabBar enabled.

[etkramer]

Version/Branch of Dear ImGui:
Version: 1.88
Branch: docking

Back-end/Renderer/Compiler/OS
Back-ends: imgui_impl_win32cpp + imgui_impl_dx12.cpp
Compiler: MSVC
Operating System: Windows 11

My Issue/Question:
With ConfigDockingAlwaysTabBar enabled, windows seem to "forget" that they're being dragged after undocking, and the user has to start a new drag in order to get it moving again.

Screenshots/Video

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

// Here's some code anyone can copy and paste to reproduce your issue
ImGui::GetIO().ConfigDockingAlwaysTabBar = true;
ImGui::Begin("Example Bug");
ImGui::End();

[ocornut]

Thanks for reporting!
Pushed a fix 3605521 by @rokups.