TextArea.SelLength
From Xojo Documentation
Property (As Integer )
aTextArea.SelLength = newIntegerValue
or
IntegerValue = aTextArea.SelLength
Supported for all project types and targets.
or
IntegerValue = aTextArea.SelLength
Supported for all project types and targets.
The number of highlighted characters.
Notes
A SelLength of 0 means an insertion point rather than a selection. A value greater than the number of characters in the TextArea means that the selection is from SelStart to the end of the TextArea.