Konrad, johnasp,
Why do you need a macro for that? I often select a block of text and insert a 1x1 table (Insert > Table > 1x1 ) while the text is selected to create a frame around an important paragraph. I use the same technique to insert a 1 cell table to later fill it with source code or other information I want to stand out. Manually setting the cell shading to yellow really makes the pseudo "text box" stand out.

I've been looking for a way to put a boarder around a block of text.
This is perfect, Thanks

What I expected after looking into the code: If I select text with the mouse and then activate the macro, I think the selected text should by to be cut out and pasted into the new cell. Instead the cell is created after the text.

It is a pitty that background-color for tables is not supported at this moment. text highlight color is not so good for alert boxes.

Anyway, thank you for your great work!

Konrad: Please explain more about what doesn't work. What code have you tried, what did you expect and what are you seeing instead. Background-color is not supported at this moment, but you can set text highlight color

Looking into the code it looks like that it should also possible to highlight a text and put it into the Single Cell. Unforutunately this does not work.

I would like to use the macro to create alert boxes. It would be great therefore, if the cell could be shaded (background-color), but it looks like this property is not supported within onetastic at the moment. Is this right?