Finds the first non-groupmaster element in the 'top group' of the GUI Stack. In other words, it actually returns the second item in the group, after the GUIRSmallWin, GUIRLargeWin, or GUIRnull item. Returns an error if there is no open GUI stack. This routine is useful for extracting information from input forms after the user quits a form or other GUI group.
c = 0 if the stack was open and this routine suceeded; 1 if the stack was closed, therefore no items to see.
hl = the first byte of the size of the first element in the top group
de = the byte after the last byte of the top group.
It is recommended that you push hl and de if you plan to use GUIFindNext; that routine requires the data of these two outputs as inputs.
a, bc, de, hl, Op1