When I try to add an another string expression just before existing one,
"}" can not be added.

1. Create new JavaFX project and add the following codes into the editor

var a=1;
var v="{a}";

2. Try to add another "{a}" just before the existing "{a}".
The expected result is

var v="{a}{a}";

3. When I typed "{a" just before "{a}",

var a=1;
var v="{a|{a}"; // "|" is cursor position.

however the next "}" can not be entered. Cursor just moved to
the following position.

var v="{a{|a}";

It should be

var v="{a}{a}";