Drag and Drop: Added ImGuiDragDropFlags_SourceNoHoldToOpenOthers flag.

imgui.cpp

@@ -5842,7 +5842,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
     bool hovered = ItemHoverable(bb, id);
 
     // Special mode for Drag and Drop where holding button pressed for a long time while dragging another item triggers the button
-    if ((flags & ImGuiButtonFlags_PressedOnDragDropHold) && g.DragDropActive && !hovered)
+    if ((flags & ImGuiButtonFlags_PressedOnDragDropHold) && g.DragDropActive && !(g.DragDropSourceFlags & ImGuiDragDropFlags_SourceNoHoldToOpenOthers))
         if (IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByActiveItem))
         {
             hovered = true;

imgui.h

@@ -597,11 +597,12 @@ enum ImGuiHoveredFlags_
 enum ImGuiDragDropFlags_
 {
     // BeginDragDropSource() flags
-    ImGuiDragDropFlags_SourceNoAutoTooltip      = 1 << 0,
-    ImGuiDragDropFlags_SourceNoDisableHover     = 1 << 1,       // By default, when dragging we clear data so that IsItemHovered() will return true, to avoid subsequent user code submitting tooltips.
-    ImGuiDragDropFlags_SourceAllowNullID        = 1 << 2,       // Allow items such as Text(), Image() that have no unique identifier to be used as drag source, by manufacturing a temporary identifier based on their window-relative position. This is extremely unusual within the dear imgui ecosystem and so we made it explicit.
-    // BeginDragDropTarget() flags
-    ImGuiDragDropFlags_AcceptBeforeDelivery     = 1 << 10,      // AcceptDragDropPayload() returns true even before the mouse button is released. You can then call IsDelivery() to test if the payload needs to be delivered.
+    ImGuiDragDropFlags_SourceNoAutoTooltip          = 1 << 0,       // By default, a successful call to BeginDragDropSource opens a tooltip so you can display a preview or description of the dragged contents. This flag disable this behavior.
+    ImGuiDragDropFlags_SourceNoDisableHover         = 1 << 1,       // By default, when dragging we clear data so that IsItemHovered() will return true, to avoid subsequent user code submitting tooltips. This flag disable this behavior so you can still call IsItemHovered() on the source item.
+    ImGuiDragDropFlags_SourceNoHoldToOpenOthers     = 1 << 2,       // Disable the behavior that allows to open tree nodes and collapsing header by holding over them while dragging a source item.
+    ImGuiDragDropFlags_SourceAllowNullID            = 1 << 3,       // Allow items such as Text(), Image() that have no unique identifier to be used as drag source, by manufacturing a temporary identifier based on their window-relative position. This is extremely unusual within the dear imgui ecosystem and so we made it explicit.
+    // AcceptDragDropPayload() flags
+    ImGuiDragDropFlags_AcceptBeforeDelivery         = 1 << 10,      // AcceptDragDropPayload() will returns true even before the mouse button is released. You can then call IsDelivery() to test if the payload needs to be delivered.
     ImGuiDragDropFlags_AcceptNoDrawDefaultRect      = 1 << 11,      // Do not draw the default highlight rectangle when hovering over target.
     ImGuiDragDropFlags_AcceptPeekOnly               = ImGuiDragDropFlags_AcceptBeforeDelivery | ImGuiDragDropFlags_AcceptNoDrawDefaultRect  // For peeking ahead and inspecting the payload before delivery.
 };

imgui_internal.h

@@ -184,7 +184,7 @@ enum ImGuiButtonFlags_
     ImGuiButtonFlags_NoKeyModifiers         = 1 << 9,   // disable interaction if a key modifier is held
     ImGuiButtonFlags_AllowOverlapMode       = 1 << 10,  // require previous frame HoveredId to either match id or be null before being usable
     ImGuiButtonFlags_NoHoldingActiveID      = 1 << 11,  // don't set ActiveId while holding the mouse (ImGuiButtonFlags_PressedOnClick only)
-    ImGuiButtonFlags_PressedOnDragDropHold  = 1 << 12   // press when held into while we are drag and dropping another item
+    ImGuiButtonFlags_PressedOnDragDropHold  = 1 << 12   // press when held into while we are drag and dropping another item (used by e.g. tree nodes, collapsing headers)
 };
 
 enum ImGuiSliderFlags_