Drag and Drop: Fixed submitting a tooltip from drop target location. Added demo.

Amend 7bbf8f2, 92b7d6b.

docs/CHANGELOG.txt

@@ -87,6 +87,8 @@ Other changes:
   - Mostly legacy behavior when used inside old Columns(), as we favored that idiom back then,
     only different is left position follows indentation level, to match calling a Separator()
     inside or outside Columns().
+- Drag and Drop: Fixed submitting a tooltip from drop target location when using AcceptDragDropPayload()
+  with ImGuiDragDropFlags_AcceptNoPreviewTooltip and submitting a tooltip manually.
 - Tables: Fixed an edge-case when no columns are visible + table scrollbar is visible + user
   code is always testing return value of TableSetColumnIndex() to coarse clip. With an active
   clipper it would have asserted. Without a clipper, the scrollbar range would be wrong.
@@ -123,6 +125,7 @@ Other changes:
 - Debug Tools: Metrics: Added "Show groups rectangles" in tools.
 - ImDrawList: Added AddEllipse(), AddEllipseFilled(), PathEllipticalArcTo(). (#2743) [@Doohl]
 - ImVector: Added find_index() helper.
+- Demo: Added "Drag and Drop -> Tooltip at target location" demo.
 - Backends: GLFW: Clear emscripten's MouseWheel callback before shutdown. (#6790, #6096, #4019) [@halx99]
 - Backends: Win32: Added support for keyboard codepage conversion for when application
   is compiled in MBCS mode and using a non-Unicode window. (#6785, #6782, #5725, #5961) [@sneakyevil]

imgui.cpp

@@ -12403,6 +12403,14 @@ void ImGui::ClearDragDrop()
     memset(&g.DragDropPayloadBufLocal, 0, sizeof(g.DragDropPayloadBufLocal));
 }
 
+bool ImGui::BeginTooltipHidden()
+{
+    ImGuiContext& g = *GImGui;
+    bool ret = Begin("##Tooltip_Hidden", NULL, ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_AlwaysAutoResize);
+    SetWindowHiddendAndSkipItemsForCurrentFrame(g.CurrentWindow);
+    return ret;
+}
+
 // When this returns true you need to: a) call SetDragDropPayload() exactly once, b) you may render the payload visual/description, c) call EndDragDropSource()
 // If the item has an identifier:
 // - This assume/require the item to be activated (typically via ButtonBehavior).
@@ -12505,12 +12513,13 @@ bool ImGui::BeginDragDropSource(ImGuiDragDropFlags flags)
         {
             // Target can request the Source to not display its tooltip (we use a dedicated flag to make this request explicit)
             // We unfortunately can't just modify the source flags and skip the call to BeginTooltip, as caller may be emitting contents.
-            bool ret = BeginTooltip();
+            bool ret;
+            if (g.DragDropAcceptIdPrev && (g.DragDropAcceptFlags & ImGuiDragDropFlags_AcceptNoPreviewTooltip))
+                ret = BeginTooltipHidden();
+            else
+                ret = BeginTooltip();
             IM_ASSERT(ret); // FIXME-NEWBEGIN: If this ever becomes false, we need to Begin("##Hidden", NULL, ImGuiWindowFlags_NoSavedSettings) + SetWindowHiddendAndSkipItemsForCurrentFrame().
             IM_UNUSED(ret);
-
-            if (g.DragDropAcceptIdPrev && (g.DragDropAcceptFlags & ImGuiDragDropFlags_AcceptNoPreviewTooltip))
-                SetWindowHiddendAndSkipItemsForCurrentFrame(g.CurrentWindow);
         }
 
         if (!(flags & ImGuiDragDropFlags_SourceNoDisableHover) && !(flags & ImGuiDragDropFlags_SourceExtern))

imgui_demo.cpp

@@ -2425,6 +2425,35 @@ static void ShowDemoWindowWidgets()
             ImGui::TreePop();
         }
 
+        IMGUI_DEMO_MARKER("Widgets/Drag and Drop/Tooltip at target location");
+        if (ImGui::TreeNode("Tooltip at target location"))
+        {
+            for (int n = 0; n < 2; n++)
+            {
+                // Drop targets
+                ImGui::Button(n ? "drop here##1" : "drop here##0");
+                if (ImGui::BeginDragDropTarget())
+                {
+                    ImGuiDragDropFlags drop_target_flags = ImGuiDragDropFlags_AcceptBeforeDelivery | ImGuiDragDropFlags_AcceptNoPreviewTooltip;
+                    if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload(IMGUI_PAYLOAD_TYPE_COLOR_4F, drop_target_flags))
+                    {
+                        ImGui::SetMouseCursor(ImGuiMouseCursor_NotAllowed);
+                        ImGui::BeginTooltip();
+                        ImGui::Text("Cannot drop here!");
+                        ImGui::EndTooltip();
+                    }
+                    ImGui::EndDragDropTarget();
+                }
+
+                // Drop source
+                static ImVec4 col4 = { 1.0f, 0.0f, 0.2f, 1.0f };
+                if (n == 0)
+                    ImGui::ColorButton("drag me", col4);
+
+            }
+            ImGui::TreePop();
+        }
+
         ImGui::TreePop();
     }
 

imgui_internal.h

@@ -3013,6 +3013,7 @@ namespace ImGui
     IMGUI_API bool          IsPopupOpen(ImGuiID id, ImGuiPopupFlags popup_flags);
     IMGUI_API bool          BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags);
     IMGUI_API bool          BeginTooltipEx(ImGuiTooltipFlags tooltip_flags, ImGuiWindowFlags extra_window_flags);
+    IMGUI_API bool          BeginTooltipHidden();
     IMGUI_API ImRect        GetPopupAllowedExtentRect(ImGuiWindow* window);
     IMGUI_API ImGuiWindow*  GetTopMostPopupModal();
     IMGUI_API ImGuiWindow*  GetTopMostAndVisiblePopupModal();