when ever i use something like:

System::Drawing::Pen ^pen= gcnew System::Drawing::Pen(System::Drawing::Color::Black, 100);

grfx = System::Drawing::Graphics::FromHwnd(this->Handle);

The GDI+ framework doesn't automatically repaint the clipping region when a WM_PAINT message comes into the message loop -- you need to handle this yourself. If it's just a couple of lines, you can simply repaint everytime you get a paint request; if it's a more complex structure you'll need an underlying model of some sort that keeps track of things.

There is also a WM_ERASEBKGND message that controls respond to to repaint thier background to match the current theme; you can set a control style to have these messages filtered.

HTH

You should ideally not use Graphics::FromHwnd, but should rather place your drawing code in the OnPaint override or the Paint event. These will pass you a PaintEventArgs that contains a graphics surface to draw to. You will also then not need the Thread::Sleep either.

The GDI+ framework doesn't automatically repaint the clipping region when a WM_PAINT message comes into the message loop -- you need to handle this yourself. If it's just a couple of lines, you can simply repaint everytime you get a paint request; if it's a more complex structure you'll need an underlying model of some sort that keeps track of things.

There is also a WM_ERASEBKGND message that controls respond to to repaint thier background to match the current theme; you can set a control style to have these messages filtered.

HTH

You should ideally not use Graphics::FromHwnd, but should rather place your drawing code in the OnPaint override or the Paint event. These will pass you a PaintEventArgs that contains a graphics surface to draw to. You will also then not need the Thread::Sleep either.