double line spacing in compose editor

[sukisen]

This is an old issue and I have looked into the answers on the forum here -
https://www.roundcubeforum.net/index.php?topic=11237.0

But it also says forced_root_block:false is deprecated, Can someone please help me on where to apply this code and whether this will work or has this been deprecated?
We are using roundcube 1.3.6

[sukisen]

solution given in above link works