what is being asked for may be solvable by skipping any force-foreground call in the minicap code, and ensuring that the print api command is used. it may not always work but providing an option to try it is worth a try.
Thanks. As I understand it in normal use the OS asks the window to repaint itself into desktop memory space when the window is moved, brought to the top, etc. So there's a good chance it's possible if the window can be asked to paint itself into a provided buffer.
I found a lot of material on capturing hidden windows in a Google search, but nothing on a simple utility that would do it.
In Minicap there's a -setfore 'Set window to be captured to foreground before capturing' switch, but it seems to be implicit as the window is always brought to the foreground without using it.
So if MiniCap can be made to capture hidden windows, maybe a -nofore switch would be one way to go. If the switch is used the program would attempt capture without bringing the window to the foreground and keeping it hidden.