2000-06-19  Dan Kuchler  <[email protected]>

        * mclistbox.tcl: Added a new binding for ButtonPress-1 to store the
        index of the row that is clicked on, so that when a drag event happens
        and the mclistbox::_init_drag_cmd os called, the index has already
        been calculated.  Previously if the drag moved too quickly the wrong
        item would be dragged.

2000-06-16  Dan Kuchler  <[email protected]>

        * mclistbox.tcl: Replaced several catch {unset varname} calls with
        if {[info exists varname]} {unset varname}.  This avoids using the
        catch, and also prevents the ::errorInfo corruption that was happening
        in mclistbox

	set binding [bind Listbox $event]
	regsub -all {%W} $binding {[::mclistbox::convert %W -W]} binding
	regsub -all {%x} $binding {[::mclistbox::convert %W -x %x]} binding
	regsub -all {%y} $binding {[::mclistbox::convert %W -y %y]} binding
	bind Mclistbox $event $binding
    }

    # Add a button press binding to track selection for drag and drop
    bind Mclistbox <ButtonPress-1> [list +::mclistbox::SetDragIndex %W %Y]

    # these define bindings for the column labels for resizing. Note
    # that we need both the name of this widget (calculated by $this)
    # as well as the specific widget that the event occured over.
    # Also note that $this is a constant string that gets evaluated
    # when the binding fires.
    # What a pain.
    set this {[::mclistbox::convert %W -W]}
    bind MclistboxMouseBindings <ButtonPress-1> \
	    "::mclistbox::ResizeEvent $this buttonpress %W %x %X %Y"
    bind MclistboxMouseBindings <ButtonRelease-1> \
	    "::mclistbox::ResizeEvent $this buttonrelease %W %x %X %Y"
    bind MclistboxMouseBindings <Enter> \
	    "::mclistbox::ResizeEvent $this motion %W %x %X %Y"
    bind MclistboxMouseBindings <Motion> \
	    "::mclistbox::ResizeEvent $this motion %W %x %X %Y"
    bind MclistboxMouseBindings <B1-Motion> \
	    "::mclistbox::ResizeEvent $this drag %W %x %X %Y"
}

# ::mclistbox::SetDragIndex --
#
#    Store the drag index when the button is first clicked so that the right
#    item is dragged and dropped.
#
# Arguments:
#
#    path          The path to the widget where the drag is started (%W from
#                  bind).
#    Y             The %Y from bind.
#
# Results:
#
#    Calculates the index of the row that was clicked in case it the item is
#    dragged.
#

proc ::mclistbox::SetDragIndex {path Y} {
    set index [$path nearest [expr {$Y - [winfo rooty $path]}]]
    set path  [::mclistbox::convert $path -W]
    upvar ::mclistbox::${path}::options options

    set options(dragIndex) $index
    
    return
}

# ::mclistbox::NewColumn --
#
#    Adds a new column to the mclistbox widget
#
# Arguments:
#

# Results:
#	{type {ops} data}
#       type     type of the data
#       ops      list of acceptable operations (copy, move and link)
#       data     the dragged data

proc ::mclistbox::_init_drag_cmd {path X Y top} {

    set path  [::mclistbox::convert $path -W]
    upvar ::mclistbox::${path}::options options

    if {[info exists options(dragIndex)]} {

        set index $options(dragIndex)

    } else {

        # I don't think this will ever happen.. We should always get a button
        # press event before the drag init is called.

        set index 0
    }

    set cmd   $options(-draginitcmd)
    if { ![string equal $cmd ""] } {
	return [uplevel \#0 $cmd [list $path $index $top]]
    }
    return [list "LISTBOX_ITEM" {copy move} $index]
}