git master: editor: tab key works incorrectly when block is marked(F3)

[slyfox]

Let's create small file:

foo
bar
quux
baz

Let's mark 'oo' substring and thentry to insert TAB in between of 'uu'.
We expect something like this:

f<F3>oo</F3>
bar
qu<--------><cursor-pos/>ux
baz

But we get:

<-------->f<F3>oo</F3>
bar
qu<cursor-pos/>ux
baz

Tab is placed at marked line, not at cursor-pos.