Fixed non-pixel aligned bounding box of window resize grip, / which triumphally led to any re-arrangement of operations inside the resize grip code outputting non-exact size_target values which led to unstable window position because clamping code uses size in a subtraction, etc etc. Lovely how a whole system can be made to act weird with a single bad input.

imgui.cpp

@@ -4386,7 +4386,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
                 // Manual resize
                 // Using the FlattenChilds button flag, we make the resize button accessible even if we are hovering over a child window
                 const ImVec2 br = window->Rect().GetBR();
-                const ImRect resize_rect(br - ImVec2(resize_corner_size * 0.75f, resize_corner_size * 0.75f), br);
+                const ImRect resize_rect(br - ImFloor(ImVec2(resize_corner_size * 0.75f, resize_corner_size * 0.75f)), br);
                 const ImGuiID resize_id = window->GetID("#RESIZE");
                 bool hovered, held;
                 ButtonBehavior(resize_rect, resize_id, &hovered, &held, ImGuiButtonFlags_FlattenChilds);