Tk Library Source Code

The attached patch updates tree.tcl to support the <<TreeSelect>> virtual event for KeyPress-Up and KeyPress-Down. Many users use the keyboard to navigate tree widgets and this brings the BWidget tree in line with current UI best practices.

Committed

Koen,
I have overseen the "select set", sorry.

So the patch is o.k., I will apply it.

Harald

Harald,
I don't understand what you mean with "select" methods. Currently, the _keynav procedure contains [selection set] commands. That seems ok to me.
Looking at the source code, I think the current_node stuff does not make any sense. It tests for [info exists selectTree::selectCursor], which is never set. Even the namespace does not exist. (Unless there is some cleverly obfuscated code where it is set -  I've not tested it.)
Koen

Thank you Koen,
what do you think of using "select" methods inside key navigation instead of the current stuff. Does the current node and selected node make any sense ?

Thank you,
Harald

I think the new patch is ok, except that it misses the first part of the "down" case in the switch statement.

Harald, I think the Tree widget does not have single/multiple selection modes like the listbox. I found some references to it in the source code, but it seems to be incomplete and there is no API to use it.

Revised patch file moves <<TreeSelect>> event firing to keyboard navigation proc (_keynav) and adds right-left arrow.

File Added - 337864: tree.patch

File Deleted - 336886:

Dear Kevin,

thank you for the patch. IMHO this is half-baken. I am not at all familiar to the tree widget, please help.

The patch proposes to also bind up and down keys to the virtual event <<TreeSelect>>.

The documentation says: Event <<TreeSelect>> fires if the selection changes. (documentation lacks the trivial fact, that it does not fire if selection changes by the select command).

The selection does not change by the up-down key bindings. Only the current node changes. In consequence, <<TreeSelect>> is not fired - that is ok.

There are IMHO multiple alternatives:

1) Change the way keyboard navigation works:
- if select mode is single, the keybard navigation will change the selection
- if select mode is multiple, the space bar should toggle selection and not expand/collapse the tree. Tree expansion/collapse may be done with the +/- keys.

2) Also fire the event <<TreeSelect>> whenn the current node changes.
A more careful patch must be created to invoke
    event generate $path <<TreeSelect>>
within
    proc Tree::_keynav
each time, the current node changes.

3) Create new event <<CurrentNode>> which is fired each time the current node changes.
(similar to 2))

The effect of the proposed patch may be achieved by two bind commands after widget creation. But key-right and key-left should also be used.

Please comment.

Thank you,
Harald

The patch can be tested with this code:

package require BWidget

Tree .t
pack .t

.t insert end root Foo -text Foo 
.t insert end root Bar -text Bar
.t insert end root Baz -text Bas

bind .t <<TreeSelect>> {puts "foo"}

The keyboard up-down buttons will print "foo" to standard output.

File Added - 336886: tree.patch