let menu button launch arbitrary floating windows

and not just menus, this is like how the gtk equivalent can launch popovers

Change-Id: I53ae96aab0c51d75405dba15ab8080d7315471e3

include/vcl/menubtn.hxx

@@ -23,6 +23,7 @@
 #include <vcl/button.hxx>
 #include <vcl/dllapi.h>
 
+class FloatingWindow;
 class Timer;
 class PopupMenu;
 class VclBuilder;
@@ -35,6 +36,7 @@ private:
 
     Timer*          mpMenuTimer;
     VclPtr<PopupMenu> mpMenu;
+    VclPtr<FloatingWindow> mpFloatingWindow;
     sal_uInt16      mnCurItemId;
     bool            mbDelayMenu;
     Link<MenuButton*,void> maActivateHdl;
@@ -73,6 +75,9 @@ public:
     void            SetPopupMenu(PopupMenu* pNewMenu);
     PopupMenu*      GetPopupMenu() const { return mpMenu; }
 
+    void            SetPopover(FloatingWindow* pFloatingWindow);
+    FloatingWindow* GetPopover() const { return mpFloatingWindow; }
+
     sal_uInt16      GetCurItemId() const { return mnCurItemId; }
     OString         GetCurItemIdent() const;
 

vcl/source/control/menubtn.cxx

@@ -20,6 +20,7 @@
 #include <tools/rc.h>
 #include <vcl/decoview.hxx>
 #include <vcl/event.hxx>
+#include <vcl/floatwin.hxx>
 #include <vcl/menu.hxx>
 #include <vcl/timer.hxx>
 #include <vcl/menubtn.hxx>
@@ -39,14 +40,24 @@ void MenuButton::ExecuteMenu()
 {
     Activate();
 
+    if (!mpMenu && !mpFloatingWindow)
+        return;
+
+    Size aSize = GetSizePixel();
+    SetPressed( true );
+    EndSelection();
     if (mpMenu)
     {
         Point aPos(0, 1);
-        Size aSize = GetSizePixel();
         Rectangle aRect(aPos, aSize );
-        SetPressed( true );
-        EndSelection();
         mnCurItemId = mpMenu->Execute(this, aRect, PopupMenuFlags::ExecuteDown);
+    }
+    else
+    {
+        Point aPos(GetParent()->OutputToScreenPixel(GetPosPixel()));
+        Rectangle aRect(aPos, aSize );
+        mpFloatingWindow->StartPopupMode(aRect, FloatWinPopupFlags::Down | FloatWinPopupFlags::GrabFocus);
+    }
     SetPressed(false);
     if (mnCurItemId)
     {
@@ -54,7 +65,6 @@ void MenuButton::ExecuteMenu()
         mnCurItemId = 0;
     }
 }
-}
 
 OString MenuButton::GetCurItemIdent() const
 {
@@ -160,6 +170,14 @@ void MenuButton::SetPopupMenu( PopupMenu* pNewMenu )
     mpMenu = pNewMenu;
 }
 
+void MenuButton::SetPopover(FloatingWindow* pFloatingWindow)
+{
+    if (pFloatingWindow == mpFloatingWindow)
+        return;
+
+    mpFloatingWindow = pFloatingWindow;
+}
+
 //class MenuToggleButton ----------------------------------------------------
 
 MenuToggleButton::MenuToggleButton( vcl::Window* pParent, WinBits nWinBits )