Hiding of number indicators while in sync editing mode when the triangle overlaps with the number

[ljubica-milovic]

Background

When the user is editing (sync mode) an antisense chain at the end of the chain or at the the gap (where numbers appear), the triangles sometimes overlap with the numbers.

Requirements

1. When the caret (sync edit mode) is placed to the right of a symbol associated with a number AND that number is >9, the number should not be visible.

This holds for editing both the sense and the antisense chains in sync mode because the umber always aligns to the right.

2. When the caret is moved from the above described position, or edit mode changed (to non-sync), or edit mode exited (view mode entered) the number should reappear.