Docking: VisibleWindow of a node spread its _NoMove attribute to the node (fixed dragging or undocking of dock node host from collapse button). (#2325, #2109)

imgui.cpp

@@ -3172,7 +3172,14 @@ void ImGui::StartMouseMovingWindow(ImGuiWindow* window)
     SetActiveID(window->MoveId, window);
     g.NavDisableHighlight = true;
     g.ActiveIdClickOffset = g.IO.MousePos - window->RootWindow->Pos;
-    if (!(window->Flags & ImGuiWindowFlags_NoMove) && !(window->RootWindow->Flags & ImGuiWindowFlags_NoMove))
+
+    bool can_move_window = true;
+    if ((window->Flags & ImGuiWindowFlags_NoMove) || (window->RootWindow->Flags & ImGuiWindowFlags_NoMove))
+        can_move_window = false;
+    if (ImGuiDockNode* node = window->DockNodeAsHost)
+        if (node->VisibleWindow && (node->VisibleWindow->Flags & ImGuiWindowFlags_NoMove))
+            can_move_window = false;
+    if (can_move_window)
         g.MovingWindow = window;
 }
 
@@ -11064,7 +11071,7 @@ static void ImGui::DockNodeStartMouseMovingWindow(ImGuiDockNode* node, ImGuiWind
     IM_ASSERT(node->WantMouseMove == true);
     ImVec2 backup_active_click_offset = g.ActiveIdClickOffset;
     StartMouseMovingWindow(window);
-    g.MovingWindow = window; // If we are docked into a non moveable root widnow, StartMouseMovingWindow() won't set g.MovingWindow. OVerride that decision.
+    g.MovingWindow = window; // If we are docked into a non moveable root window, StartMouseMovingWindow() won't set g.MovingWindow. Override that decision.
     node->WantMouseMove = false;
     g.ActiveIdClickOffset = backup_active_click_offset;
 }
@@ -11533,6 +11540,8 @@ static void ImGui::DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_w
         if (IsMouseClicked(0))
         {
             focus_tab_id = tab_bar->SelectedTabId;
+
+            // Forward moving request to selected window
             if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, focus_tab_id))
                 StartMouseMovingWindow(tab->Window);
         }

imgui_widgets.cpp

@@ -712,7 +712,7 @@ bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_no
     if (IsItemActive() && IsMouseDragging(0))
     {
         bool can_extract_dock_node = false;
-        if (dock_node != NULL)
+        if (dock_node != NULL && dock_node->VisibleWindow && !(dock_node->VisibleWindow->Flags & ImGuiWindowFlags_NoMove))
         {
             ImGuiDockNode* root_node = DockNodeGetRootNode(dock_node);
             if (root_node->OnlyNodeWithWindows != dock_node || (root_node->CentralNode != NULL))