Added GetMousePosOnOpeningCurrentPopup().

imgui.cpp

@@ -2826,6 +2826,14 @@ ImVec2 ImGui::GetMousePos()
     return GImGui->IO.MousePos;
 }
 
+ImVec2 ImGui::GetMousePosOnOpeningCurrentPopup()
+{
+    ImGuiState& g = *GImGui;
+	if (g.CurrentPopupStack.Size > 0)
+		return g.OpenedPopupStack[g.CurrentPopupStack.Size-1].MousePosOnOpen;
+	return g.IO.MousePos;
+}
+
 ImVec2 ImGui::GetMouseDragDelta(int button, float lock_threshold)
 {
     ImGuiState& g = *GImGui;
@@ -2982,7 +2990,7 @@ void ImGui::OpenPopup(const char* str_id)
     ImGuiWindow* window = GetCurrentWindow();
     ImGuiID id = window->GetID(str_id);
     int current_stack_size = g.CurrentPopupStack.Size;
-    ImGuiPopupRef popup_ref = ImGuiPopupRef(id, window, window->GetID("##menus")); // Tagged as new ref because constructor sets Window to NULL (we are passing the ParentWindow info here)
+    ImGuiPopupRef popup_ref = ImGuiPopupRef(id, window, window->GetID("##menus"), g.IO.MousePos); // Tagged as new ref because constructor sets Window to NULL (we are passing the ParentWindow info here)
     if (g.OpenedPopupStack.Size < current_stack_size + 1)
         g.OpenedPopupStack.push_back(popup_ref);
     else if (g.OpenedPopupStack[current_stack_size].PopupID != id)

imgui.h

@@ -398,6 +398,7 @@ namespace ImGui
     IMGUI_API bool          IsMouseHoveringRect(const ImVec2& pos_min, const ImVec2& pos_max);  // is mouse hovering given bounding rect (in screen space). clipped by current clipping settings. disregarding of consideration of focus/window ordering/blocked by a popup.
     IMGUI_API bool          IsMouseDragging(int button = 0, float lock_threshold = -1.0f);      // is mouse dragging. if lock_threshold < -1.0f uses io.MouseDraggingThreshold
     IMGUI_API ImVec2        GetMousePos();                                                      // shortcut to ImGui::GetIO().MousePos provided by user, to be consistent with other calls
+	IMGUI_API ImVec2		GetMousePosOnOpeningCurrentPopup();									// retrieve backup of mouse positioning at the time of opening popup we have BeginPopup() into
     IMGUI_API ImVec2        GetMouseDragDelta(int button = 0, float lock_threshold = -1.0f);    // dragging amount since clicking, also see: GetItemActiveDragDelta(). if lock_threshold < -1.0f uses io.MouseDraggingThreshold
     IMGUI_API void          ResetMouseDragDelta(int button = 0);                                // 
     IMGUI_API ImGuiMouseCursor GetMouseCursor();                                                // get desired cursor type, reset in ImGui::NewFrame(), this updated during the frame. valid before Render(). If you use software rendering by setting io.MouseDrawCursor ImGui will render those for you

imgui_internal.h

@@ -305,8 +305,9 @@ struct ImGuiPopupRef
     ImGuiWindow*        Window;         // Resolved on BeginPopup() - may stay unresolved if user never calls OpenPopup()
     ImGuiWindow*        ParentWindow;   // Set on OpenPopup()
     ImGuiID             ParentMenuSet;  // Set on OpenPopup()
+	ImVec2				MousePosOnOpen;	// Copy of mouse position at the time of opening popup
 
-    ImGuiPopupRef(ImGuiID id, ImGuiWindow* parent_window, ImGuiID parent_menu_set) { PopupID = id; Window = NULL; ParentWindow = parent_window; ParentMenuSet = parent_menu_set; }
+    ImGuiPopupRef(ImGuiID id, ImGuiWindow* parent_window, ImGuiID parent_menu_set, const ImVec2& mouse_pos) { PopupID = id; Window = NULL; ParentWindow = parent_window; ParentMenuSet = parent_menu_set; MousePosOnOpen = mouse_pos; }
 };
 
 // Main state for ImGui