Well this already was a tricky one in AutoCAD, but it is possible if you define the attribute text as an multiline text.

Is there a way in Draftsight, that I add a backround-mask to an attribute-text?
I use a couple of attributes on my blocks, and want to "highlight" one of them. 
Below you see an example of such block.
The "TAG-number" may vary in length, why I'd like to use a backround-mask for the text.