Demo: Tree selection demo use !IsItemToggledOpen() (#1896) + update FAQ (#4366)

docs/FAQ.md

@@ -23,7 +23,7 @@ or view this file with any Markdown viewer.
 | [I integrated Dear ImGui in my engine and some elements are clipping or disappearing when I move windows around...](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-clipping-or-disappearing-when-i-move-windows-around) |
 | [I integrated Dear ImGui in my engine and some elements are displaying outside their expected windows boundaries...](#q-i-integrated-dear-imgui-in-my-engine-and-some-elements-are-displaying-outside-their-expected-windows-boundaries) |
 | **Q&A: Usage** |
-| **[About the ID Stack system..<br>Why is my widget not reacting when I click on it?<br>How can I have widgets with an empty label?<br>How can I have multiple widgets with the same label?](#q-about-the-id-stack-system)** |
+| **[About the ID Stack system..<br>Why is my widget not reacting when I click on it?<br>How can I have widgets with an empty label?<br>How can I have multiple widgets with the same label?]<br>How can I have multiple windows with the same label?](#q-about-the-id-stack-system)** |
 | [How can I display an image? What is ImTextureID, how does it work?](#q-how-can-i-display-an-image-what-is-imtextureid-how-does-it-work)|
 | [How can I use my own math types instead of ImVec2/ImVec4?](#q-how-can-i-use-my-own-math-types-instead-of-imvec2imvec4) |
 | [How can I interact with standard C++ types (such as std::string and std::vector)?](#q-how-can-i-interact-with-standard-c-types-such-as-stdstring-and-stdvector) |
@@ -190,6 +190,7 @@ Refer to rendering backends in the [examples/](https://github.com/ocornut/imgui/
 ### Q: Why is my widget not reacting when I click on it?
 ### Q: How can I have widgets with an empty label?
 ### Q: How can I have multiple widgets with the same label?
+### Q: How can I have multiple windows with the same label?
 
 A primer on labels and the ID Stack...
 

imgui.cpp

@@ -723,9 +723,11 @@ CODE
  Q&A: Usage
  ----------
 
- Q: Why is my widget not reacting when I click on it?
+ Q: About the ID Stack system..
- Q: How can I have widgets with an empty label?
+   - Why is my widget not reacting when I click on it?
- Q: How can I have multiple widgets with the same label?
+   - How can I have widgets with an empty label?
+   - How can I have multiple widgets with the same label?
+   - How can I have multiple windows with the same label?
  Q: How can I display an image? What is ImTextureID, how does it works?
  Q: How can I use my own math types instead of ImVec2/ImVec4?
  Q: How can I interact with standard C++ types (such as std::string and std::vector)?

imgui_demo.cpp

@@ -786,6 +786,7 @@ static void ShowDemoWindowWidgets()
             for (int i = 0; i < 6; i++)
             {
                 // Disable the default "open on single-click behavior" + set Selected flag according to our selection.
+                // To alter selection we use IsItemClicked() && !IsItemToggledOpen(), so clicking on an arrow doesn't alter selection.
                 ImGuiTreeNodeFlags node_flags = base_flags;
                 const bool is_selected = (selection_mask & (1 << i)) != 0;
                 if (is_selected)
@@ -794,7 +795,7 @@ static void ShowDemoWindowWidgets()
                 {
                     // Items 0..2 are Tree Node
                     bool node_open = ImGui::TreeNodeEx((void*)(intptr_t)i, node_flags, "Selectable Node %d", i);
-                    if (ImGui::IsItemClicked())
+                    if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen())
                         node_clicked = i;
                     if (test_drag_and_drop && ImGui::BeginDragDropSource())
                     {
@@ -815,7 +816,7 @@ static void ShowDemoWindowWidgets()
                     // use BulletText() or advance the cursor by GetTreeNodeToLabelSpacing() and call Text().
                     node_flags |= ImGuiTreeNodeFlags_Leaf | ImGuiTreeNodeFlags_NoTreePushOnOpen; // ImGuiTreeNodeFlags_Bullet
                     ImGui::TreeNodeEx((void*)(intptr_t)i, node_flags, "Selectable Leaf %d", i);
-                    if (ImGui::IsItemClicked())
+                    if (ImGui::IsItemClicked() && !ImGui::IsItemToggledOpen())
                         node_clicked = i;
                     if (test_drag_and_drop && ImGui::BeginDragDropSource())
                     {