I have a view where I added position fixed to the style of the root. It works as expected in the client, but on the designer, if I click on any of the children of the root, then the view crashes. The only way to fix it is to set the position back to relative, change what I need to change, then put it back to fixed. As a work around, I added a binding to it that checks if I am on the designer and set the position accordingly. It works, but not ideal.
And while we are on the topic of position, when I do position absolute, on the designer, the object is moved to where I indicate, but the border indicating the object selected is not moved with it. This is more annoying than it is a real problem, but if you are fixing one issue, maybe you could look at the other too.