Hot to set a richtext box in Pencil (wireframing tool) to a custom width

Question

Hi,

I'm creating a prototype with Pencil an open source wireframing and mocking tool. I need to add a rich text box to my prototype and fill it with some sample text. The problem is that the box automatically resizes it self to around 200px and it won't budge from that width no matter what I do.

I need to know how to set a custom width for a pencil rich text box.