Windows: add StopMouseMovingWindow(), partial merge 80d78fa from docking.

imgui.cpp

@@ -4503,15 +4503,6 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
     // Clear previous active id
     if (g.ActiveId != 0)
     {
-        // While most behaved code would make an effort to not steal active id during window move/drag operations,
-        // we at least need to be resilient to it. Canceling the move is rather aggressive and users of 'master' branch
-        // may prefer the weird ill-defined half working situation ('docking' did assert), so may need to rework that.
-        if (g.MovingWindow != NULL && g.ActiveId == g.MovingWindow->MoveId)
-        {
-            IMGUI_DEBUG_LOG_ACTIVEID("SetActiveID() cancel MovingWindow\n");
-            g.MovingWindow = NULL;
-        }
-
         // Store deactivate data
         ImGuiDeactivatedItemData* deactivated_data = &g.DeactivatedItemData;
         deactivated_data->ID = g.ActiveId;
@@ -4524,6 +4515,15 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
         // One common scenario leading to this is: pressing Key ->NavMoveRequestApplyResult() -> ClearActiveID()
         if (g.InputTextState.ID == g.ActiveId)
             InputTextDeactivateHook(g.ActiveId);
+
+        // While most behaved code would make an effort to not steal active id during window move/drag operations,
+        // we at least need to be resilient to it. Canceling the move is rather aggressive and users of 'master' branch
+        // may prefer the weird ill-defined half working situation ('docking' did assert), so may need to rework that.
+        if (g.MovingWindow != NULL && g.ActiveId == g.MovingWindow->MoveId)
+        {
+            IMGUI_DEBUG_LOG_ACTIVEID("SetActiveID() cancel MovingWindow\n");
+            StopMouseMovingWindow();
+        }
     }
 
     // Set active id
@@ -5077,6 +5077,19 @@ void ImGui::StartMouseMovingWindow(ImGuiWindow* window)
         g.MovingWindow = window;
 }
 
+// This is not 100% symetric with StartMouseMovingWindow().
+// We do NOT clear ActiveID, because:
+// - It would lead to rather confusing recursive code paths. Caller can call ClearActiveID() if desired.
+// - Some code intentionally cancel moving but keep the ActiveID to lock inputs (e.g. code path taken when clicking a disabled item).
+void ImGui::StopMouseMovingWindow()
+{
+    ImGuiContext& g = *GImGui;
+
+    // [nb: docking branch has more stuff in this function]
+
+    g.MovingWindow = NULL;
+}
+
 // Handle mouse moving window
 // Note: moving window with the navigation keys (Square + d-pad / CTRL+TAB + Arrows) are processed in NavUpdateWindowing()
 // FIXME: We don't have strong guarantee that g.MovingWindow stay synced with g.ActiveId == g.MovingWindow->MoveId.
@@ -5100,7 +5113,7 @@ void ImGui::UpdateMouseMovingWindowNewFrame()
         }
         else
         {
-            g.MovingWindow = NULL;
+            StopMouseMovingWindow();
             ClearActiveID();
         }
     }
@@ -5142,6 +5155,9 @@ void ImGui::UpdateMouseMovingWindowEndFrame()
         {
             StartMouseMovingWindow(g.HoveredWindow); //-V595
 
+            // FIXME: In principal we might be able to call StopMouseMovingWindow() below.
+            // Please note how StartMouseMovingWindow() and StopMouseMovingWindow() and not entirely symetrical, at the later doesn't clear ActiveId.
+
             // Cancel moving if clicked outside of title bar
             if (g.IO.ConfigWindowsMoveFromTitleBarOnly)
                 if (!(root_window->Flags & ImGuiWindowFlags_NoTitleBar))

imgui_internal.h

@@ -3150,6 +3150,7 @@ namespace ImGui
     IMGUI_API void          UpdateHoveredWindowAndCaptureFlags(const ImVec2& mouse_pos);
     IMGUI_API void          FindHoveredWindowEx(const ImVec2& pos, bool find_first_and_in_any_viewport, ImGuiWindow** out_hovered_window, ImGuiWindow** out_hovered_window_under_moving_window);
     IMGUI_API void          StartMouseMovingWindow(ImGuiWindow* window);
+    IMGUI_API void          StopMouseMovingWindow();
     IMGUI_API void          UpdateMouseMovingWindowNewFrame();
     IMGUI_API void          UpdateMouseMovingWindowEndFrame();