Docking: storing window menu handler in a function pointer to allow customizing menu (undocumented)

imgui.cpp

@@ -14646,7 +14646,8 @@ namespace ImGui
     static void             DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_window);
     static void             DockNodeAddTabBar(ImGuiDockNode* node);
     static void             DockNodeRemoveTabBar(ImGuiDockNode* node);
-    static ImGuiID          DockNodeUpdateWindowMenu(ImGuiDockNode* node, ImGuiTabBar* tab_bar);
+    static void             DockNodeWindowMenuUpdate(ImGuiDockNode* node, ImGuiTabBar* tab_bar);
+    static void             DockNodeWindowMenuHandler_Default(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);
     static void             DockNodeUpdateVisibleFlag(ImGuiDockNode* node);
     static void             DockNodeStartMouseMovingWindow(ImGuiDockNode* node, ImGuiWindow* window);
     static bool             DockNodeIsDropAllowed(ImGuiWindow* host_window, ImGuiWindow* payload_window);
@@ -14720,6 +14721,8 @@ void ImGui::DockContextInitialize(ImGuiContext* ctx)
     ini_handler.ApplyAllFn = DockSettingsHandler_ApplyAll;
     ini_handler.WriteAllFn = DockSettingsHandler_WriteAll;
     g.SettingsHandlers.push_back(ini_handler);
+
+    g.DockNodeWindowMenuHandler = &DockNodeWindowMenuHandler_Default;
 }
 
 void ImGui::DockContextShutdown(ImGuiContext* ctx)
@@ -16122,11 +16125,39 @@ static int IMGUI_CDECL TabItemComparerByDockOrder(const void* lhs, const void* r
     return (a->BeginOrderWithinContext - b->BeginOrderWithinContext);
 }
 
-static ImGuiID ImGui::DockNodeUpdateWindowMenu(ImGuiDockNode* node, ImGuiTabBar* tab_bar)
+// Default handler for g.DockNodeWindowMenuHandler(): display the list of windows for a given dock-node.
+// This is exceptionally stored in a function pointer to also user applications to tweak this menu (undocumented)
+// Custom overrides may want to decorate, group, sort entries.
+// Please note those are internal structures: if you copy this expect occasional breakage.
+static void ImGui::DockNodeWindowMenuHandler_Default(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar)
+{
+    IM_UNUSED(ctx);
+    if (tab_bar->Tabs.Size == 1)
+    {
+        // "Hide tab bar" option. Being one of our rare user-facing string we pull it from a table.
+        if (MenuItem(LocalizeGetMsg(ImGuiLocKey_DockingHideTabBar), NULL, node->IsHiddenTabBar()))
+            node->WantHiddenTabBarToggle = true;
+    }
+    else
+    {
+        // Display a selectable list of windows in this docking node
+        for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+        {
+            ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+            if (tab->Flags & ImGuiTabItemFlags_Button)
+                continue;
+            if (Selectable(TabBarGetTabName(tab_bar, tab), tab->ID == tab_bar->SelectedTabId))
+                TabBarQueueFocus(tab_bar, tab);
+            SameLine();
+            Text("   ");
+        }
+    }
+}
+
+static void ImGui::DockNodeWindowMenuUpdate(ImGuiDockNode* node, ImGuiTabBar* tab_bar)
 {
     // Try to position the menu so it is more likely to stays within the same viewport
     ImGuiContext& g = *GImGui;
-    ImGuiID ret_tab_id = 0;
     if (g.Style.WindowMenuButtonPosition == ImGuiDir_Left)
         SetNextWindowPos(ImVec2(node->Pos.x, node->Pos.y + GetFrameHeight()), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
     else
@@ -16134,27 +16165,9 @@ static ImGuiID ImGui::DockNodeUpdateWindowMenu(ImGuiDockNode* node, ImGuiTabBar*
     if (BeginPopup("#WindowMenu"))
     {
         node->IsFocused = true;
-        if (tab_bar->Tabs.Size == 1)
-        {
-            if (MenuItem(LocalizeGetMsg(ImGuiLocKey_DockingHideTabBar), NULL, node->IsHiddenTabBar()))
-                node->WantHiddenTabBarToggle = true;
-        }
-        else
-        {
-            for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
-            {
-                ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
-                if (tab->Flags & ImGuiTabItemFlags_Button)
-                    continue;
-                if (Selectable(TabBarGetTabName(tab_bar, tab), tab->ID == tab_bar->SelectedTabId))
-                    ret_tab_id = tab->ID;
-                SameLine();
-                Text("   ");
-            }
-        }
+        g.DockNodeWindowMenuHandler(&g, node, tab_bar);
         EndPopup();
     }
-    return ret_tab_id;
 }
 
 // User helper to append/amend into a dock node tab bar. Most commonly used to add e.g. a "+" button.
@@ -16267,8 +16280,10 @@ static void ImGui::DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_w
     // FIXME-DOCK FIXME-OPT: Could we recycle popups id across multiple dock nodes?
     if (has_window_menu_button && IsPopupOpen("#WindowMenu"))
     {
-        if (ImGuiID tab_id = DockNodeUpdateWindowMenu(node, tab_bar))
-            focus_tab_id = tab_bar->NextSelectedTabId = tab_id;
+        ImGuiID next_selected_tab_id = tab_bar->NextSelectedTabId;
+        DockNodeWindowMenuUpdate(node, tab_bar);
+        if (tab_bar->NextSelectedTabId != 0 && tab_bar->NextSelectedTabId != next_selected_tab_id)
+            focus_tab_id = tab_bar->NextSelectedTabId;
         is_focused |= node->IsFocused;
     }
 

imgui_internal.h

@@ -2163,6 +2163,7 @@ struct ImGuiContext
     // Extensions
     // FIXME: We could provide an API to register one slot in an array held in ImGuiContext?
     ImGuiDockContext        DockContext;
+    void                    (*DockNodeWindowMenuHandler)(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);
 
     // Settings
     bool                    SettingsLoaded;
@@ -2356,6 +2357,8 @@ struct ImGuiContext
         PlatformImeViewport = 0;
         PlatformLocaleDecimalPoint = '.';
 
+        DockNodeWindowMenuHandler = NULL;
+
         SettingsLoaded = false;
         SettingsDirtyTimer = 0.0f;
         HookIdNext = 0;