Text element block size

Here's a link to the gif file : www.mesfichiers.info/fc2/blockvDesigner.gif

(I edited /plugins/vmcustom/designtool/designtool/tmpl/default.php by adding another case to have a custom design)

Is there a way to define a width and height for a test element ?
I have an element which contains a long text. When I edit it, the block becomes smaller and go center. This is very annoying as I have to replace manually every text block after changing the text

I attached a gif of the thing, just to show exactly what is annoying.