diff --git a/lcl/interfaces/qt/qtwinapi.inc b/lcl/interfaces/qt/qtwinapi.inc
index 73a9705c12..3d856ef793 100644
--- a/lcl/interfaces/qt/qtwinapi.inc
+++ b/lcl/interfaces/qt/qtwinapi.inc
@@ -90,10 +90,18 @@ end;
   Returns:
  ------------------------------------------------------------------------------}
 function TQtWidgetSet.ClientToScreen(Handle: HWND; var P: TPoint) : Boolean;
+var
+  APoint: TQtPoint;
 begin
   Result := True;
   if Handle <> 0 then
-    QWidget_mapToGlobal(TQtWidget(Handle).Widget, @P, @P);
+  begin
+    APoint.x := P.X;
+    APoint.y := P.Y;
+    QWidget_mapToGlobal(TQtWidget(Handle).Widget, @APoint, @APoint);
+    P.X := APoint.x;
+    P.Y := APoint.y;
+  end;
 end;
 
 {------------------------------------------------------------------------------
@@ -2376,6 +2384,63 @@ begin
   Result := True;
 end;
 
+{------------------------------------------------------------------------------
+  Function: PolyBezier
+  Params:  DC: HDC; Points: PPoint; NumPts: Integer; Filled: Boolean;
+           Continuous: Boolean
+  Returns: Nothing
+ ------------------------------------------------------------------------------}
+function TQtWidgetSet.PolyBezier(DC: HDC; Points: PPoint; NumPts: Integer;
+  Filled, Continuous: Boolean): Boolean;
+begin
+  {$ifdef VerboseQtWinAPI}
+    WriteLn('[WinAPI PolyBezier] DC: ', dbghex(DC));
+  {$endif}
+  Result := inherited PolyBezier(DC, Points, NumPts, Filled, Continuous);
+end;
+
+{------------------------------------------------------------------------------
+  Function: Polygon
+  Params:  DC: HDC; Points: PPoint; NumPts: Integer; Winding: Boolean
+  Returns: Nothing
+ ------------------------------------------------------------------------------}
+function TQtWidgetSet.Polygon(DC: HDC; Points: PPoint; NumPts: Integer;
+  Winding: Boolean): boolean;
+var
+  ARect: TRect;
+  ADC : TQtDeviceContext;
+begin
+  {$ifdef VerboseQtWinAPI}
+    WriteLn('[WinAPI Polygon] DC: ', dbghex(DC));
+  {$endif}
+  Result := IsValidDC(DC);
+  if Result then
+  begin
+    {TODO: discuss with other developers about antialiasing by default}
+    // QPainter_setRenderHint(TQtDeviceContext(DC).Widget, QPainterAntialiasing, True);
+    if Winding
+    then
+      QPainter_drawPolygon(TQtDeviceContext(DC).Widget, PQtPoint(Points), NumPts, QtWindingFill)
+    else
+      QPainter_drawPolygon(TQtDeviceContext(DC).Widget, PQtPoint(Points), NumPts, QtOddEvenFill);
+  end;
+end;
+
+{------------------------------------------------------------------------------
+  Function: Polyline
+  Params:  DC: HDC; Points: PPoint; NumPts: Integer
+  Returns: Nothing
+ ------------------------------------------------------------------------------}
+function TQtWidgetSet.Polyline(DC: HDC; Points: PPoint; NumPts: Integer): boolean;
+begin
+  {$ifdef VerboseQtWinAPI}
+    WriteLn('[WinAPI Polyline] DC: ', dbghex(DC));
+  {$endif}
+  Result := IsValidDC(DC);
+  if Result then
+    QPainter_drawPolyline(TQtDeviceContext(DC).Widget, PQtPoint(Points), NumPts);
+end;
+
 {------------------------------------------------------------------------------
   Function: Rectangle
   Params:  DC: HDC; X1, Y1, X2, Y2: Integer
diff --git a/lcl/interfaces/qt/qtwinapih.inc b/lcl/interfaces/qt/qtwinapih.inc
index 0830bd2ff8..8a31581c36 100644
--- a/lcl/interfaces/qt/qtwinapih.inc
+++ b/lcl/interfaces/qt/qtwinapih.inc
@@ -95,6 +95,10 @@ function LineTo(DC: HDC; X, Y: Integer): Boolean; override;
 
 function MoveToEx(DC: HDC; X, Y: Integer; OldPoint: PPoint): Boolean; override;
 
+function PolyBezier(DC: HDC; Points: PPoint; NumPts: Integer; Filled, Continuous: boolean): boolean; override;
+function Polygon(DC: HDC; Points: PPoint; NumPts: Integer; Winding: boolean): boolean; override;
+function Polyline(DC: HDC; Points: PPoint; NumPts: Integer): boolean; override;
+
 function Rectangle(DC: HDC; X1, Y1, X2, Y2: Integer): Boolean; override;
 function ReleaseDC(hWnd: HWND; DC: HDC): Integer; override;
 function RestoreDC(DC: HDC; SavedDC: Integer): Boolean; override;