How to reproduce:
Actual behavior: when you type the text, the zero-width column selection becomes a selection from column 1 to column 10, and the text typed fills the entire selection.
- Type some text and turn off column mode.
- Put cursor on line 1, column 10.
- Select some text by holding shift and pressing down arrow.
- With the text selected, turn on column mode. This will display a zero-width column selected.
- Type some text.
Actual behavior: when you type the text, the zero-width column selection becomes a selection from column 1 to column 10, and the text typed fills the entire selection.