Demo: some TreeNode layout examples (#414, #282)

imgui_demo.cpp

@@ -91,7 +91,7 @@ void ImGui::ShowUserGuide()
 }
 
 // Demonstrate most ImGui features (big function!)
-void ImGui::ShowTestWindow(bool* opened)
+void ImGui::ShowTestWindow(bool* p_opened)
 {
     // Examples apps
     static bool show_app_metrics = false;
@@ -145,7 +145,7 @@ void ImGui::ShowTestWindow(bool* opened)
     if (no_scrollbar) window_flags |= ImGuiWindowFlags_NoScrollbar;
     if (no_collapse)  window_flags |= ImGuiWindowFlags_NoCollapse;
     if (!no_menu)     window_flags |= ImGuiWindowFlags_MenuBar;
-    if (!ImGui::Begin("ImGui Demo", opened, ImVec2(550,680), bg_alpha, window_flags))
+    if (!ImGui::Begin("ImGui Demo", p_opened, ImVec2(550,680), bg_alpha, window_flags))
     {
         // Early out if the window is collapsed, as an optimization.
         ImGui::End();
@@ -779,7 +779,7 @@ void ImGui::ShowTestWindow(bool* opened)
             ImGui::TreePop();
         }
 
-        if (ImGui::TreeNode("Widgets Alignment"))
+        if (ImGui::TreeNode("Widgets Width"))
         {
             static float f = 0.0f;
             ImGui::Text("PushItemWidth(100)");
@@ -950,6 +950,17 @@ void ImGui::ShowTestWindow(bool* opened)
             ImGui::Text("Widget"); ImGui::SameLine();
             ImGui::SmallButton("Widget");
 
+            // Tree
+            const float spacing = ImGui::GetStyle().ItemInnerSpacing.x;
+            ImGui::Button("Button##1"); 
+            ImGui::SameLine(0.0f, spacing); 
+            if (ImGui::TreeNode("Node##1")) { for (int i = 0; i < 6; i++) ImGui::BulletText("Item %d..", i); ImGui::TreePop(); }    // Dummy tree data
+
+            ImGui::AlignFirstTextHeightToWidgets();         // Vertically align text node a bit lower so it'll be vertically centered with upcoming widget. Otherwise you can use SmallButton (smaller fit).
+            bool tree_opened = ImGui::TreeNode("Node##2");  // Common mistake to avoid: if we want to SameLine after TreeNode we need to do it before we add child content.
+            ImGui::SameLine(0.0f, spacing); ImGui::Button("Button##2");
+            if (tree_opened) { for (int i = 0; i < 6; i++) ImGui::BulletText("Item %d..", i); ImGui::TreePop(); }   // Dummy tree data
+
             ImGui::TreePop();
         }