IE6-8: Can't execute link commnad twice in a row

[Jakub Ś]

To reproduce:

1. Go to usage of the api sample
2. Use "Set editor Contents"
3. Use "Insert Text" (text should be inserted at the beginning)
4. Click at the end of text and use "Insert Text" (text should be inserted at the end)
5. Select with some and use "Execute Link Command"
6. Type anything and press Ok
7. Use "Execute Link Command" again

Result: focus goes to first line (see video)

[Jakub Ś]

Reproducible from rev. [7518]

[Jakub Ś]

#9127 is also broken by [7518]

[Wiktor Walc]

I can confirm it in IE6 as well.

[Garry Yao]

Fixed with [7560].