A wxScreenDC can be used to paint on the screen. This should normally be constructed as a temporary stack object; don't store a wxScreenDC object.
wxDC, wxMemoryDC, wxPaintDC, wxClientDC, wxWindowDC
Use this in conjunction with EndDrawingOnTop to ensure that drawing to the screen occurs on top of existing windows. Without this, some window systems (such as X) only allow drawing to take place underneath other windows.
By using the first form of this function, an application is specifying that the area that will be drawn on coincides with the given window.
By using the second form, an application can specify an area of the screen which is to be drawn on. If NULL is passed, the whole screen is available.
It is recommended that an area of the screen is specified because with large regions, flickering effects are noticeable when destroying the temporary transparent window used to implement this feature.
You might use this pair of functions when implementing a drag feature, for example as in the wxSplitterWindow implementation.
This function is probably obsolete since the X implementations allow drawing directly on the screen now. However, the fact that this function allows the screen to be refreshed afterwards, may be useful to some applications.
Use this in conjunction with StartDrawingOnTop.
This function destroys the temporary window created to implement on-top drawing (X only).ymasuda 平成17年11月19日