Some tags have mandatory input areas. Rather than pop up a dialog as other applications do, (which I happen to hate :) GTKeyboard prints the full tag out to the output section, and then places the cursor (or point) at the location where the first input is needed.
Example: When clicking on the LINK item in the HTML menu, the following text is inserted into the output buffer:
<A HREF=''''></A>
GTKeyboard will then place the point between the set of quotation marks, where the first input for the link is expected, i.e. the target of the link. (Note: Sometimes the cursor doesn't appear to be in the right place right after a tag has been inserted, but it is.)