Question

I was wondering if there was any way through C# or C++ to send to fake or otherwise trick a program into thinking it has focus? I’m thinking that there’s a message you can send to it using SendMessage/PostMessage that’ll trick it into having focus.

Answer 1

There is no guaranteed way to trick it into thinking it has focus because there are multiple ways it can check if it has focus. For example, it could be checking for WM_SETFOCUS and then checking it is out of focus when it receives WM_KILLFOCUS. So you could trick it in this case by sending intercepting all WM_KILLFOCUS messages with a window hook.

However, it might also be checking for if it has focus by calling GetFocus. So to trick it in that scenario, you would need to detour GetFocus and fake the return value. You can try both of these methods and they might work and they might not, but I wouldn’t expect them to work reliably.