Selects a range of characters in the label, if the label is selectable.
See set_selectable. If the label is not selectable, this function has no
effect. If start_offset
or end_offset
are -1, then the end of the label will be substituted.
this |
a Label |
start_offset |
start offset (in characters not bytes) |
end_offset |
end offset (in characters not bytes) |