Docking: Fixed an issue where removing the last window from a dockspace node that is not a central node without remove the node. (#2414, #2109)

imgui.cpp

@@ -11432,7 +11432,7 @@ static void ImGui::DockNodeRemoveWindow(ImGuiDockNode* node, ImGuiWindow* window
         }
     }
 
-    if (node->Windows.Size == 0 && !node->IsCentralNode && window->DockId != node->ID)
+    if (node->Windows.Size == 0 && !node->IsCentralNode && !node->IsDockSpace() && window->DockId != node->ID)
     {
         // Automatic dock node delete themselves if they are not holding at least one tab
         DockContextRemoveNode(&g, node, true);
@@ -11631,7 +11631,7 @@ static void ImGui::DockNodeUpdateVisibleFlagAndInactiveChilds(ImGuiDockNode* nod
 static void ImGui::DockNodeUpdateVisibleFlag(ImGuiDockNode* node)
 {
     // Update visibility flag
-    bool is_visible = (node->ParentNode == 0) ? node->IsDockSpace() : node->IsCentralNode;
+    bool is_visible = (node->ParentNode == NULL) ? node->IsDockSpace() : node->IsCentralNode;
     is_visible |= (node->Windows.Size > 0);
     is_visible |= (node->ChildNodes[0] && node->ChildNodes[0]->IsVisible);
     is_visible |= (node->ChildNodes[1] && node->ChildNodes[1]->IsVisible);

imgui_internal.h

@@ -1670,7 +1670,7 @@ namespace ImGui
     IMGUI_API void          DockBuilderDockWindow(const char* window_name, ImGuiID node_id);
     IMGUI_API ImGuiDockNode*DockBuilderGetNode(ImGuiID node_id);                    // Warning: DO NOT HOLD ON ImGuiDockNode* pointer, will be invalided by any split/merge/remove operation.
     inline ImGuiDockNode*   DockBuilderGetCentralNode(ImGuiID node_id)              { ImGuiDockNode* node = DockBuilderGetNode(node_id); if (!node) return NULL; return DockNodeGetRootNode(node)->CentralNode; }
-    IMGUI_API ImGuiID       DockBuilderAddNode(ImGuiID node_id, ImGuiDockNodeFlags flags = 0);
+    IMGUI_API ImGuiID       DockBuilderAddNode(ImGuiID node_id, ImGuiDockNodeFlags flags = 0);  // Use (flags == ImGuiDockNodeFlags_Dockspace) to create a dockspace, otherwise it'll create a floating node.
     IMGUI_API void          DockBuilderRemoveNode(ImGuiID node_id);                 // Remove node and all its child, undock all windows
     IMGUI_API void          DockBuilderRemoveNodeDockedWindows(ImGuiID node_id, bool clear_persistent_docking_references = true);
     IMGUI_API void          DockBuilderRemoveNodeChildNodes(ImGuiID node_id);       // Remove all split/hierarchy. All remaining docked windows will be re-docked to the root.