[LyX/master] Fix backspace deletion of selected items with change tracking

[Jean-Marc Lasgouttes]

Le 13/01/2020 à 16:00, Jürgen Spitzmüller a écrit :
> Am Montag, den 13.01.2020, 15:48 +0100 schrieb Jean-Marc Lasgouttes:
>> If I switch on change tracking before inserting  a column in a
>> tabular,
>> there is no way to know what column is new.
> 
> I see a change bar in the margin.

Yes, but you do not know what column was added.

BTW, the changebar in the margin has a height computed as

	int const height = tm_.isLastRow(row_)
		? row_.ascent()
		: row_.height();

This lead to ridiculously small bars in cells for example. Does anyone 
know why we do not use the row height every time?

JMarc