Issue #1668

i.e. linehandle.on, markedrange.off, etc.

Issue #1654

Removed "pos" parameter.

Fixed clipping of the insertAt index.

And turn the hack off in recent Chrome builds.

Issue #1663

Closes #1662

Use it to prevent some unneeded state computation.

Issue #1653

Move hinting functions into it.

Issue #1617

Issue #1645

(When they are above visible range, scroll up to correspond for
height reduction.)

Closes #1645

Since the addon is called merge, not diff.

Which could result in a selection at a negative character offset
when double-clicking.

Issue #1638

Issue #1084
Issue #1630

Apparenly Firefox still hasn't caught up on the unprefixed version.