We have a custom RDP client that we've built using the RDP ActiveX control and MFC: https://docs.microsoft.com/en-us/windows/win32/termserv/using-remote-desktop-web-connection
In order to support multiple monitors, we use the put_UseMultimon function: https://docs.microsoft.com/en-us/windows/win32/termserv/imsrdpclientnonscriptable5-usemultimon
This kind of works, but we have to manually stretch the window across the monitors. Maximizing the window will maximize it on one of the monitors. The experience we get is not so good, we can't really use the entire area, and the window title bar remains (when maximizing the window on one screen it disappears).
We would like to get an experience similar to mstsc, where maximizing the window will change it's style to maximized and make the window span on the entire area. Is there a way to maximize a window and make it span across all monitors?
WM_GETMINMAXINFO
you get to control your maximized size and position. Not sure if the OS will let you overlap multiple monitors or not but probably worth a try. – Jonathan Potter