Initial popup window.

src/ui_elements/desktop_elements/Window.h

@@ -6,6 +6,7 @@
 #include <vector>
 #include <cstdint>
 #include <string>
+#include <functional>
 
 class PaintEvent;
 class MouseEvent;
@@ -30,6 +31,8 @@ class Window : public DrawingSurface
 
 public:
 
+    using onPopupFunc = std::function<void(mt::Window* parent, std::unique_ptr<Widget> popup)>;
+
     Window();
 
     ~Window();
@@ -72,11 +75,37 @@ public:
         return mTitle;
     }
 
+    void addPopup(std::unique_ptr<Widget> popupWidget)
+    {
+        if (mPopupFunc)
+        {
+            mPopupFunc(this, std::move(popupWidget));
+        }
+    }
+
+    void setPopupHandler(onPopupFunc func)
+    {
+        mPopupFunc = func;
+    }
+
+    void setParent(Window* parent)
+    {
+        mParent = parent;
+    }
+
+    Window* getParent() const
+    {
+        return mParent;
+    }
+
 private:
     WidgetPtr mWidget {nullptr};
     std::string mTitle;
     IPlatformWindowPtr mPlatformWindow {nullptr};
     std::unique_ptr<DrawingContext> mDrawingContext;
+
+    onPopupFunc mPopupFunc;
+    Window* mParent{nullptr};
 };
 }