do {
    next if ($answer == wxCANCEL);
    pce::edit::restore_positions;
}
until (pce::document::select_next == $first_doc);

C:\Documents and Settings\M01169>perldoc -f do
    do BLOCK
            Not really a function. Returns the value of the last command in
            the sequence of commands indicated by BLOCK. When modified by a
            loop modifier, executes the BLOCK once before testing the loop
            condition. (On other statements the loop modifiers test the
            conditional first.)

            "do BLOCK" does *not* count as a loop, so the loop control
            statements "next", "last", or "redo" cannot be used to leave or
            restart the block. See perlsyn for alternative strategies.
...

while(&pce::document::select_next != $first_doc); {      
next if ($answer == wxCANCEL);
       & pce::edit:: save_positions;
       //$answer = &sniff_selection(0, $sci_frame->GetTextLength);
&pce::edit::restore_positions;
}
 

           do {{
               next if $x == $y;
               # do something here
           }} until $x++ > $z;

           LOOP: {
                   do {
                       last if $x = $y**2;
                       # do something here
                   } while $x++ <= $z;
           }