Re: Clicking "select" button in qt plots hampers ginput() operation

[Philip Nienhuis]

Mike Miller wrote:
> On Sun, Oct 30, 2016 at 07:55:44 -0700, Philip Nienhuis wrote:
> > (This may be due to me not understanding fully what the "select" button in Qt
> > plot windows does.)
> >
> > I find that ginput() in qt plots, as soon as the select button (the arrow)
> > is clicked any number of times, calls of the form:
> >
> > [x, y, b] = ginput ()
> >
> > return only empty output after several mouse clicks in the plot, and
> >
> > [x, y, b] = ginput (1)
> > -or-
> > [x, y, b] = ginput (N)   #  (where N is a positive integer)
> >
> > simply does not return after a mouse click as I believe it should (and also
> > returns empty output). On Linux hitting the Return key helps, on Windows
> > this doesn't help and Octave even gets hung.
> >
> > The way out is to click e.g., the zoom-in ("+") button twice - that
> > apparently disengages the "select" button action.
> >
> > Is this a bug? If yes I'll enter a bug report for it.
> > If not a bug, what is the "select" button good for? I'd assume it should
> > work a.o., to help ginput() "select" a point.
> >
> > (FYI: I hit this when invoking ginput() on plots that were zoomed in - I
> > clicked "select" to disengage the zoom-in button rather than clicking the
> > zoom-in button another time)
>
> The "select" button doesn't act as a toggle, it only sets the figure's
> mouse mode to "select". The only way to reset the figure mouse mode to
> "none" is to click either of the "rotate" or "pan" buttons twice.

... or one of the zoom buttons.

> The "select" button sets the hidden property "__mouse_mode__" to the
> enumerated value "select". I don't know what this mode does or how it
> interacts with the normal event listeners that are used to implement the
> ginput() function, but hopefully this helps you.

It helps to know that you also don't know what "select" mode is supposed 
to do.
One of the reasons I asked is that on gnuplot and fltk there appears to 
be no "select" mode that can be selected with the mouse.

Maybe one of the other devs knows a little more?

Philip