Selection handles need a large enough hit size
Aliases: selection handle · drag handle · text grabber
What it is
A touch selection has a handle at each end; dragging a handle moves the boundary to a chosen character gap. The handle is painted on the text’s anchor, but the finger has to hit the handle’s own target. If that target is as small as the type size, people are not adjusting a selection. They are trying to grab a point that will not be grabbed.
Why it happens
The handle’s visual may be a droplet or a stem; the hit region must be enlarged on its own. Once the drag starts, the boundary follows the contact, which the finger pad still covers, so people see the handle’s visual and aim at a region they cannot see. If the hit region is too small, the first press lands on the text and is read as “cancel selection, place caret,” and the selection vanishes. When handles sit close (one or two characters selected), hit regions overlap; the drag takes the wrong end and the selection grows the wrong way. Handles therefore have to exceed finger-pad error and still be distinguishable as left versus right on a short selection. They solve “grab the boundary,” not “see the covered letters”—seeing is the magnifier’s job.
Studying it
Have people expand a selection from one word to specified start and end characters, varying handle diameter, inter-handle distance, and whether handles may cross. Log grab failures (selection cancelled), wrong-end grabs, and overshoot during the drag. Independent variables include type size and one-handed thumb. Split “missed the handle” from “grabbed it but the gap is wrong.” The latter is gap precision; the former is handle size.
Where it stops holding
Mouse-drag across text has no handle control; this claim does not apply. A pen tip can hit a smaller handle, but overlap of two handles still has to be prevented. Keyboard Shift+arrows extend a selection and bypass handles. “Copy the whole block” on read-only text can reduce handle use; it does not remove the need to select on arbitrary boundaries.
Applying it
- Size handle hit regions for touch, not for type size; the visual may be smaller than the hit region.
- On short selections, offset the two handles vertically or enforce a minimum gap so one press cannot hit both ends.
- Walk “select two or three characters, then drag each end”: if the selection often vanishes on tap, enlarge the handle before adding a magnifier.