You will need to have the olwm window manager run in the mode where focus follows the mouse (in this mode, your keystrokes go to whatever window your mouse points to); to do this, find the line in your .xinitrc file that invokes olwm; add the option -follow to the olwm command. If, for some reason, you must run olwm in the click-to-focus mode, you must click the mouse in each window before pigi will accept keyboard commands in that window; it is possible but annoying to use pigi this way. An alternative is to add the following line to your .Xdefaults file:

OpenWindows.SetInput:	followmouse