TreeNode: Fixed bug where BeginDragDropSource() failed when the _OpenOnDoubleClick flag is set. Added basic demo code. (Amend 05420ea)

docs/CHANGELOG.txt

@@ -34,11 +34,21 @@ HOW TO UPDATE?
  VERSION 1.77 WIP (In Progress)
 -----------------------------------------------------------------------
 
+Breaking Changes:
+
+Other Changes:
+
+- TreeNode: Fixed bug where BeginDragDropSource() failed when the _OpenOnDoubleClick flag is
+  enabled (bug introduced in 1.76, but pre-1.76 it would also fail unless the _OpenOnArrow
+  flag was also set, and _OpenOnArrow is frequently set along with _OpenOnDoubleClick).
+
 
 -----------------------------------------------------------------------
  VERSION 1.76 (Released 2020-04-12)
 -----------------------------------------------------------------------
 
+Decorated log: https://github.com/ocornut/imgui/releases/tag/v1.76
+
 Other Changes:
 
 - Drag and Drop, Nav: Disabling navigation arrow keys when drag and drop is active. In the docking

imgui_demo.cpp

@@ -641,11 +641,13 @@ static void ShowDemoWindowWidgets()
             HelpMarker("This is a more typical looking tree with selectable nodes.\nClick to select, CTRL+Click to toggle, click on arrows or double-click to open.");
             static ImGuiTreeNodeFlags base_flags = ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick | ImGuiTreeNodeFlags_SpanAvailWidth;
             static bool align_label_with_current_x_position = false;
+            static bool test_drag_and_drop = false;
             ImGui::CheckboxFlags("ImGuiTreeNodeFlags_OpenOnArrow", (unsigned int*)&base_flags, ImGuiTreeNodeFlags_OpenOnArrow);
             ImGui::CheckboxFlags("ImGuiTreeNodeFlags_OpenOnDoubleClick", (unsigned int*)&base_flags, ImGuiTreeNodeFlags_OpenOnDoubleClick);
             ImGui::CheckboxFlags("ImGuiTreeNodeFlags_SpanAvailWidth", (unsigned int*)&base_flags, ImGuiTreeNodeFlags_SpanAvailWidth); ImGui::SameLine(); HelpMarker("Extend hit area to all available width instead of allowing more items to be layed out after the node.");
             ImGui::CheckboxFlags("ImGuiTreeNodeFlags_SpanFullWidth", (unsigned int*)&base_flags, ImGuiTreeNodeFlags_SpanFullWidth);
             ImGui::Checkbox("Align label with current X position", &align_label_with_current_x_position);
+            ImGui::Checkbox("Test tree node as drag source", &test_drag_and_drop);
             ImGui::Text("Hello!");
             if (align_label_with_current_x_position)
                 ImGui::Unindent(ImGui::GetTreeNodeToLabelSpacing());
@@ -665,6 +667,12 @@ static void ShowDemoWindowWidgets()
                     bool node_open = ImGui::TreeNodeEx((void*)(intptr_t)i, node_flags, "Selectable Node %d", i);
                     if (ImGui::IsItemClicked())
                         node_clicked = i;
+                    if (test_drag_and_drop && ImGui::BeginDragDropSource())
+                    {
+                        ImGui::SetDragDropPayload("_TREENODE", NULL, 0);
+                        ImGui::Text("This is a drag and drop source");
+                        ImGui::EndDragDropSource();
+                    }
                     if (node_open)
                     {
                         ImGui::BulletText("Blah blah\nBlah Blah");
@@ -680,6 +688,12 @@ static void ShowDemoWindowWidgets()
                     ImGui::TreeNodeEx((void*)(intptr_t)i, node_flags, "Selectable Leaf %d", i);
                     if (ImGui::IsItemClicked())
                         node_clicked = i;
+                    if (test_drag_and_drop && ImGui::BeginDragDropSource())
+                    {
+                        ImGui::SetDragDropPayload("_TREENODE", NULL, 0);
+                        ImGui::Text("This is a drag and drop source");
+                        ImGui::EndDragDropSource();
+                    }
                 }
             }
             if (node_clicked != -1)

imgui_widgets.cpp

@@ -5360,10 +5360,11 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
     // It is rather standard that arrow click react on Down rather than Up and we'd be tempted to make it the default
     // (by removing the _OpenOnArrow test below), however this would have a perhaps surprising effect on CollapsingHeader()?
     // So right now we are making this optional. May evolve later.
+    // We set ImGuiButtonFlags_PressedOnClickRelease on OpenOnDoubleClick because we want the item to be active on the initial MouseDown in order for drag and drop to work.
     if (is_mouse_x_over_arrow && (flags & ImGuiTreeNodeFlags_OpenOnArrow))
         button_flags |= ImGuiButtonFlags_PressedOnClick;
     else if (flags & ImGuiTreeNodeFlags_OpenOnDoubleClick)
-        button_flags |= ImGuiButtonFlags_PressedOnDoubleClick;
+        button_flags |= ImGuiButtonFlags_PressedOnClickRelease | ImGuiButtonFlags_PressedOnDoubleClick;
     else
         button_flags |= ImGuiButtonFlags_PressedOnClickRelease;