[Tile-dev] ttk::treeview -selectmode option; please review.

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

For review: proposed '-selectmode' option for the ttk::treeview widget.

|   Command-Line Name:-selectmode
|   Database Name:  selectMode
|   Database Class: SelectMode
|
|	  Controls how the built-in class bindings manage  the  selection.
|	  One of multiple, single, or none.
|
|	  If  set  to  multiple  (the  default),  multiple  items  may  be
|	  selected.  If single, only a single item will be selected  at  a
|	  time.  If none, the selection will not be changed.
|
|	  Note  that  application code and tag bindings can set the selec-
|	  tion however they wish, regardless of the value of  -selectmode.


This is (intentionally) a minimal set, intended to cover only
the two most common use cases.  If applications need something
different, they can use '-selectmode none' and implement
whatever behaviour they want in widget and/or tag bindings.
This should (hopefully!) not be too difficult.

Other potentially-useful selection modes I can think of are:

Single-selection submodes:
    + selection optional or exactly one item selected?
    + independent focus or focus item linked to selection?

Multiple-selection submodes:
    + contiguous or disjoint selection?
    + "anchored" mode or "expansion" mode when extending selection?
    + <B1-Motion>: extend selection, or begin drag-and-drop?

Current choices are: focus item linked to selection in 'single' mode;
selection extension uses "anchored" mode (anchor is the focus item);
disjoint selections are allowed; <B1-Motion> is currently a no-op.

'-selectmode extended' and '-selectmode browse' were omitted on purpose.
These are well-established, but not, I think, terribly well-defined.



--Joe English

  jen...@fl...