There are two ways to choose a window to redirect data from the keyboard to. They are the implicit method, and the explicit method. The implicit method, which is the default, is quite easy. Whichever window had the focus last is the window that is designated to receive the key presses. The explicit mode is where the user chooses a window explicitly for redirection.
In order to use the implicit mode, all you have to do is make sure that the window you want to redirect to is the window that last had the keyboard focus in your window manager. That's it. Generally, if you need to assign this, you can just click on the window you want to focus on with your mouse, and then click on GTKeyboard again. You should see a message in your status window saying ``Found new focus window: window name'' All keyboard usage after that will go into the foreign window.
In order to choose a new window to redirect output to (using explicit mode), click on the Output menu, then click on Choose a Window. Your cursor will change, at which time you go out and choose a window by clicking on an active window. When that is done, you just type with the on-screen keyboard as normal, or do whatever you would normally do, except that output goes into the foreign window rather than where it usually goes. See the BUGS file that comes withe the source distribution about some things that don't seem to want to work properly like xterm which are traditionally a pain to send X events to. For most things, this will work just that easily. (e.g. an rxvt window/other terminal emulator)
Sometimes, you will want to redirect text to a certain box within a certain window. (Like for example, the URL box in Netscape Navigator). This is no problem, GTKeyboard will let you do that too, but you must make sure that the box you want to type into has the focus. Basically, after you select the window, click on the box that you want one more time so a thin black border comes up around it as is traditional for most windows that have the focus, and then you can begin typing into that window.
Some notes about redirection to other windows:
You will also find a ``Choose Window'' and ``Ignore Window'' option under the Shortcuts menu. They're just there for convenience, there is no difference between them, only that some people look in different places for the same things.
The ignore window button does exactly what it says it does: It ignores the current active window. So if you're workin on something within an rxvt window, and you want to go back to editing within the GTKeyboard text buffer, click on the Ignore Window button either at the bottom of the screen or in the Shortcuts or Output menus, and GTKeyboard will take focus away from that window and begin sending all keystrokes back into the GTKeyboard editing buffer. This allows you the flexibility to flip back and forth between small editing tasks editing in other windows or performing other tasks with the on screen keyboard.