I'm quite the novice when it comes to Visio, and I can't say that it has been a very pleasant experience so far..
I have a set of shapes that are copies of one another. They are to be placed into a panel to illustrate a segment control. Now I want to have all the shapes selected and resize their width together to find the right width for them inside the panel. The problem I'm experiencing is that once I start resizing their width they "pop" in height making them about 50% higher than before I started resizing.
This is how it behaves:
Before resizing

Started resizing

There is probably some relation between the height/width of shapes in Visio that I'm unaware of that is the cause of what's happening, but I can't seem to figure out how to get around it.
Btw, it's not as easy as setting back the height once I've adjusted the width. Once the shapes have popped to a new height I can't lower the height any more.