diff --git a/src/osx/cocoa/nonownedwnd.mm b/src/osx/cocoa/nonownedwnd.mm
index c118d47b08..f38eeddde4 100644
--- a/src/osx/cocoa/nonownedwnd.mm
+++ b/src/osx/cocoa/nonownedwnd.mm
@@ -997,6 +997,13 @@ void wxNonOwnedWindowCocoaImpl::GetContentArea( int& left, int &top, int &width,
 
 bool wxNonOwnedWindowCocoaImpl::SetShape(const wxRegion& WXUNUSED(region))
 {
+    // macOS caches the contour of the drawn area, so when the region is changed and the content view redrawn
+    // the shape of the tlw does not change, this is a workaround I found that leads to a contour-refresh ...
+    NSRect formerFrame = [m_macWindow frame];
+    NSSize formerSize = [NSWindow contentRectForFrameRect:formerFrame styleMask:[m_macWindow styleMask]].size;
+    [m_macWindow setContentSize:NSMakeSize(10,10)];
+    [m_macWindow setContentSize:formerSize];
+
     [m_macWindow setOpaque:NO];
     [m_macWindow setBackgroundColor:[NSColor clearColor]];
 
diff --git a/src/osx/nonownedwnd_osx.cpp b/src/osx/nonownedwnd_osx.cpp
index d17624f029..d5118be241 100644
--- a/src/osx/nonownedwnd_osx.cpp
+++ b/src/osx/nonownedwnd_osx.cpp
@@ -510,6 +510,7 @@ void *wxNonOwnedWindow::OSXGetViewOrWindow() const
 bool wxNonOwnedWindow::DoClearShape()
 {
     m_shape.Clear();
+    m_shapePath = wxGraphicsPath();
 
     wxSize sz = GetClientSize();
     wxRegion region(0, 0, sz.x, sz.y);
@@ -519,11 +520,13 @@ bool wxNonOwnedWindow::DoClearShape()
 
 bool wxNonOwnedWindow::DoSetRegionShape(const wxRegion& region)
 {
+    m_shapePath = wxGraphicsPath();
     m_shape = region;
 
     // set the native content view to transparency, this is an implementation detail
     // no reflected in the wx BackgroundStyle
     GetPeer()->SetBackgroundStyle(wxBG_STYLE_TRANSPARENT);
+    GetPeer()->SetNeedsDisplay();
 
     return m_nowpeer->SetShape(region);
 }
@@ -534,8 +537,6 @@ bool wxNonOwnedWindow::DoSetRegionShape(const wxRegion& region)
 
 bool wxNonOwnedWindow::DoSetPathShape(const wxGraphicsPath& path)
 {
-    m_shapePath = path;
-
     // Convert the path to wxRegion by rendering the path on a window-sized
     // bitmap, creating a mask from it and finally creating the region from
     // this mask.
@@ -548,12 +549,18 @@ bool wxNonOwnedWindow::DoSetPathShape(const wxGraphicsPath& path)
 
         wxScopedPtr<wxGraphicsContext> context(wxGraphicsContext::Create(dc));
         context->SetBrush(*wxWHITE);
-        context->FillPath(m_shapePath);
+        context->FillPath(path);
     }
 
     bmp.SetMask(new wxMask(bmp, *wxBLACK));
 
-    return DoSetRegionShape(wxRegion(bmp));
+    // the shape path has to be set AFTER the region is set, because that method
+    // clears any former path
+    bool success = DoSetRegionShape(wxRegion(bmp));
+    if ( success )
+        m_shapePath = path;
+
+    return success;
 }
 
 void