For example, you click on a character
in the middle of a line, delete, and
the cursor runs to the end.
Hm, it does not? Are you manually shifting focus? Any script in OnTextChanged?
How to remove the ability to select a
line / part of a line by holding down
the mouse button in Editable Text?
I believe you’d need to set it to Not Hit-Testable as isReadOnly merely prevents inputting. Other than that, you could try wrapping the editable text with a user widget and passing Unhandled in onMouseDown - untested, though; could work.