[Tile-dev] Scale widget

[Joe E. <jen...@fl...>]

The [ttk::scale] widget is currently missing a few features
relative to the core [scale] widget.

I use the core [scale] widget a lot, and am perpetually
frustrated by various quirks and irregularities, so
I'd like to propose that the [ttk::scale] widget
*not* be completely compatible with it :-)

First: I think it's safe to desupport '-showvalue true'.
No other toolkit uses this visual idiom that I'm aware of,
and there are more effective ways to achieve the same effect.

The [scale] widget tends to invoke the -command at unusual
times, and it's unpredictable when the linked -variable is
adjusted to match -from, -to, and -resolution.  This makes it 
difficult to use [scale]s as input/output widgets.

(Even worse: the behavior has changed between Tk 8.4 and
the current CVS HEAD, and I can't find any clue as to why.)

Vertical [scale]s move the slider from the top of the widget
to the bottom as the value changes between -from and -to.
While this is consistent with Tk's coordinate system --
the Y axis points downwards -- it runs contrary to user
expectations.  IOW: horizontal scales should set -from=min
and -to=max, while vertical scales should set -from=max
and -to=min.  The [ttk::scale] widget should rectify this.

The scale has "-length" and "-width" options, where "-width"
actually specifies the height of horizontal scales.  This 
option should be renamed "-thickness" (or left out entirely 
and let the theme decide, like the [ttk:scrollbar] does).

Finally: scale widgets and spinboxes have a similar function --
both are "valuator" widgets -- so it would be a good idea to
make the widget API's as similar as possible.

Any other thoughts?


--Joe English

  jen...@fl...