Docking: Fixed an issue where windows docked into a node that's part of their dockspace wouldn't recover their order correctly after init. (#2109)

(It only worked on floating dock node for the accidental reason that BeginDocked would generally early out on the first frame)

imgui.cpp

@@ -13507,8 +13507,9 @@ void ImGui::BeginDocked(ImGuiWindow* window, bool* p_open)
     else
         window->Flags &= ~ImGuiWindowFlags_NoTitleBar;      // Clear the NoTitleBar flag in case the user set it: confusingly enough we need a title bar height so we are correctly offset, but it won't be displayed!
 
-    // Save new dock order only if the tab bar is active
-    if (node->TabBar)
+    // Save new dock order only if the tab bar has been visible once.
+    // This allows multiple windows to be created in the same frame and have their respective dock orders preserved.
+    if (node->TabBar && node->TabBar->CurrFrameVisible != -1)
         window->DockOrder = (short)DockNodeGetTabOrder(window);
 
     if ((node->WantCloseAll || node->WantCloseTabID == window->ID) && p_open != NULL)