McBopomofo allows users to input pheases with a different length of the
characters and Bopomofo readings, for example, users can input ∴ with ㄙㄨㄛˇ-ㄧˇ.
When the cursor if between ㄙㄨㄛˇ and ㄧˇ, the users have no clue where
the cursor exactly is. The tooltip is to tell the users the cursor is
now betwen ㄙㄨㄛˇ and ㄧˇ.
zonble