Conference bulova::decw_jan-89_to_nov-90

242.0. "Same sender and receiver of Global Selection" by EPIK::BUEHLER (Delusion dilutes) Fri Feb 17 1989 15:27

    I'm having a bit of trouble with Global Selections.  I can move
    information (STRING and TARGET) back and forth without any problems. 
    But when I try to have my application both provide and receive the
    selection things go haywire.  I get stuck in an infinite loop of:
    
    1. Ask for selection (TARGETs)
    
    2. Callback1 is called and it provides list of targets
    
    3. Callback2 is called and it checks the list of targets to see if
       STRING is a valid TARGET.  It is, so it calls
       XtGetSelectionValueIncremental(STRING).
    
    4. Callback1 is immediately invoked and it provides the selection in
       STRING form, as requested.  This call *immediately* follows the
       Incremental call in (3) - immediate as seen through a single STEP in
       the debugger.
    
    5. Back to 2.
    
    The obvious difficulty is that I'm not receiving the STRING data. 
    Instead, the toolkit keeps requesting the list of targets from
    Callback1, which takes us back through the whole mess again.  I was
    using CurrentTime for a while and recently changed over to using the
    latest event times from the X event stream.
    
    Does any of this ring any bells?
    
John

    Serves me right.  Put the note in the wrong bloody file.
    
    Turns out it was pilot error.  I was using the Incremental support and
    wasn't handling the transmission or reception of the data correctly.  I
    had to both transmit the data followed by a zero length transmission
    and understand that such a construction was going to be sent to the
    receiving code.
    
    Great fun.
    
John