tk_getOpenFile -multiple 1 on linux, selection behaviour

Activestate Tk 8.5.11, also the just released 8.5.12, OpenSuse 11.4 (if it matters)

While tk_getOpenFile -multiple 1 on windows opens a file dialog which
behaves as other dialogs allowing multiple selections of items (dragging
the mouse selects multiple items, Control-mouse adds a single item to
the selection, Shift-keyboard traversal also selects multiple items),

on Linux the behaviour is strange IMHO:
- in order to select multiple items I have to Shift-Drag the mouse
(would have expected simple drag)
- multiple selection via keyboard using shfit-up/down is not possible at all
(would have expected to Shift-Arrow-Up/Down-select files)

This comes unexpected, since:
- Control-mouse selects a single item as expected
- Shift-Mouse also extends the selection as expected

Even if -multiple 0 is specified, Shift-Mouse-Motion draws a selection
where it shouldn't. While it actually selects only a single item, it
shows multiple as selected.

Also if the mouse leaves the window, the selected items are no longer
shown as selected (though the selection still exists and is re-shown if
changed).