Docking: Fixed splitting/docking into a node that has buttons amended…

… into tab bar. Windows were not moved correctly. (#5515)

imgui.cpp

@@ -14738,10 +14738,14 @@ static void ImGui::DockNodeMoveWindows(ImGuiDockNode* dst_node, ImGuiDockNode* s
         src_node->TabBar = NULL;
     }
 
-    for (int n = 0; n < src_node->Windows.Size; n++)
+    for (int n_from_node = 0, n_from_tab_bar = 0; n_from_node < src_node->Windows.Size; n_from_node++, n_from_tab_bar++)
     {
         // DockNode's TabBar may have non-window Tabs manually appended by user
-        if (ImGuiWindow* window = src_tab_bar ? src_tab_bar->Tabs[n].Window : src_node->Windows[n])
+        while (src_tab_bar && src_tab_bar->Tabs[n_from_tab_bar].Window == NULL)
+            n_from_tab_bar++;
+
+        // Using TabBar order (FIXME: Why? Clarify + add tests for it)
+        if (ImGuiWindow* window = src_tab_bar ? src_tab_bar->Tabs[n_from_tab_bar].Window : src_node->Windows[n_from_node])
         {
             window->DockNode = NULL;
             window->DockIsActive = false;