After one or more width markers are selected, the tool can perform several operations on them:
While the tool does not support dragging to change the width of a marker (the native Width tool can still be used for this purpose), it can adjust the widths of one or more markers simultaneously if the preference Use Increase/Decrease Diameter Keys is set to Change Stroke Width. In this case the keys assigned to Decrease Diameter and Increase Diameter in the native Keyboard Shortcuts dialog (the left and right square bracket keys respectively, by default, for English language keyboards) will decrease or increase their widths, using the numerical Change Width value set on the Width Selector panel.
Dragging one or more selected width markers will move them along the path. A width marker may not be moved past the previous or next unselected marker, and the markers at the start and end of the path cannot be moved at all (therefore, if the selection includes either the end or start marker, it won’t be able to be moved either). Dragging a marker until it contacts another marker and releasing the mouse button will create a doubled marker, which may be used to produce an abrupt change in stroke width:
Width Selector Dragging Markers
To “stretch” markers (move a contiguous selection of one or more markers as a group while proportionally shifting all the other markers on the path, except those at the start and end of the path), hold down Shift
while dragging them:
Width Selector Stretching Markers
To duplicate one or more selected width markers, hold down the Option/Alt
key after starting to drag them:
Width Selector Duplicating Markers
The Width Selector tool can add a new width marker to a stroke by holding down Option/Alt
and then clicking along the path. The new marker’s initial width will be equal to the current width of the stroke at that point.
Width Selector Adding Marker
When a variable width stroke is used on a compound path, all of the subpaths must share the same width profile. So selecting one or more width markers on one subpath with the Width Selector tool will automatically select the same markers on all of the subpaths:
Width Selector and Compound Paths