[Octave-bug-tracker] [bug #54083] Qt toolkit figures don't always redraw on resize until releasing the mouse button

[Dan Sebald]

URL:
  <http://savannah.gnu.org/bugs/?54083>

                 Summary: Qt toolkit figures don't always redraw on resize
until releasing the mouse button
                 Project: GNU Octave
            Submitted by: sebald
            Submitted on: Thu 07 Jun 2018 09:39:48 PM UTC
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

First, I just want to note that it's fairly well known that Qt graphics
toolkit resizing has this black background flash.  I think that has to do with
a delay introduced to lessen a multi-threading bug.  However, now the FLTK
graphics toolkit is exhibiting the same black-background flash that I know it
never used to have.  In the FLTK case there isn't a threading issue.  So, I'm
wondering if there were a fix for Qt in a way that caused the FLTK situation
to arise.

The bug of the Summary is probably closely related to the above paragraph. 
I've notice when resizing a Qt window (not FLTK) that the plot redraws
sometimes but not always.  That is, there are some cases where I dragged the
Figure window slightly bigger but the plot itself does not adjust...not until
I release the mouse button--then the plot is redrawn to correctly fill the
available space.  So, it seems as though the plot isn't being redrawn with
every mouse event, just select events.  Could it be that some of those events
are being lost because a redraw/re-render is busy?




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