Fixed window inner clipping rectangle off by one when window is located on a monitor with negative coordinates. (#6861, #2884)

docs/CHANGELOG.txt

@@ -102,6 +102,9 @@ Other changes:
 
 Docking+Viewports Branch:
 
+- Viewports: Fixed window inner clipping rectangle off by one when window is located on a monitor
+  with negative coordinates. While it is expected that other small issues with arise from this
+  situation, at the moment we are fixing the most noticeable one. (#6861, #2884) [@Vuhdo, @alektron]
 - Docking: Fixed an issue leading to incorrect restoration of selected tab in dock nodes that
   don't carry the currently focused window. (#2304)
 - Docking: added ImGuiDockNodeFlags_NoUndocking. (#2999, #6823, #6780, #3492)

imgui.cpp

@@ -7155,10 +7155,10 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         // Affected by window/frame border size. Used by:
         // - Begin() initial clip rect
         float top_border_size = (((flags & ImGuiWindowFlags_MenuBar) || !(flags & ImGuiWindowFlags_NoTitleBar)) ? style.FrameBorderSize : window->WindowBorderSize);
-        window->InnerClipRect.Min.x = ImFloor(0.5f + window->InnerRect.Min.x + ImMax(ImFloor(window->WindowPadding.x * 0.5f), window->WindowBorderSize));
-        window->InnerClipRect.Min.y = ImFloor(0.5f + window->InnerRect.Min.y + top_border_size);
-        window->InnerClipRect.Max.x = ImFloor(0.5f + window->InnerRect.Max.x - ImMax(ImFloor(window->WindowPadding.x * 0.5f), window->WindowBorderSize));
-        window->InnerClipRect.Max.y = ImFloor(0.5f + window->InnerRect.Max.y - window->WindowBorderSize);
+        window->InnerClipRect.Min.x = ImFloorSigned(0.5f + window->InnerRect.Min.x + ImMax(ImFloor(window->WindowPadding.x * 0.5f), window->WindowBorderSize));
+        window->InnerClipRect.Min.y = ImFloorSigned(0.5f + window->InnerRect.Min.y + top_border_size);
+        window->InnerClipRect.Max.x = ImFloorSigned(0.5f + window->InnerRect.Max.x - ImMax(ImFloor(window->WindowPadding.x * 0.5f), window->WindowBorderSize));
+        window->InnerClipRect.Max.y = ImFloorSigned(0.5f + window->InnerRect.Max.y - window->WindowBorderSize);
         window->InnerClipRect.ClipWithFull(host_rect);
 
         // Default item width. Make it proportional to window size if window manually resizes