#153 Provide expected tab stop behavior

[Dave Hein]

This patch file is for Tk8.4.2. It modifies
generic/tkTextDisp.c.

The problem is that the text widget has unusual tabbing
behavior that doesn't match the expectations of users.
The patch changes the tab stop behavior to match most
user's expectations.

Here is an example that demonstrates the strange
behavior (note that '\t' means hit the Tab key, and
'\n\ means hit the Enter or Return key):

In "wish" create the text widget using:

text .t -width 40 -height 20 -font {"Courier" 10} -tabs
{30 left 60 90 120 150}
pack .t

Then set the focus on the text widget and type
"\tx\tx\tx\tx\nxxxxx\tx\txx\tx\tx". In the unpatched
code you will see:

bbbbxbbxbbxbbx
xxxxxbxbxxbxbx

As you can see (adjusting for proportional font
distortions), the tabs are not moving the insertion
point to the expected tab stops.

After applying the patch, typing that same string yielded:

bbbbxbbxbbxbbx
xxxxxbxbbxxbxbbx

This time, the tab stops are honored and the insertion
points are where we expect them to be.

NOTE: I did not invent this patch. While search for a
solution to the problem I found this patch given at
this webpage:

http://www.qs.co.nz/Tcl/TkTabs.html

--
Dave Hein

[Dave Hein]

Patch file for tk8.4.2 to fix text widget tab problem

[Vince Darley]

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Ok, I've tested with 8.5 and this has been fixed, along with
many other text widget problems.

[Donal K. Fellows]

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So, should this patch be applied to the 8.4 branch or dropped?

[Vince Darley]

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Good idea to apply patch to 8.4, I would say.

If someone has the time/inclination it would be good to
backport many other fixes from 8.5a0 (see Tk's changelog for
the long list of bugs which have been fixed). The problem
is that these fixes are to an objectified text widget but
8.4 is char*-based, so backporting is not always trivial. A
valuable if somewhat dull exercise ;-).

[Vince Darley]

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Probably too late to apply to 8.4, but assigning to Jeff in
case.

[Jeffrey Hobbs]

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Taken care of in 8.5