It seems to me that when a form is opened as a pop-up, this form is not really centered in the browser. This gets worse if the form is also given a specific width and/or height, it seems that, in that perticular case that the form is first opened somewhat centered with the default size and is then resized to the specified size without recentering the pop-up. I've tested this with a tiny test project in the 4.2.1 modeler and with a larger styled project in the 4.2 modeler and in both cases this behaviour is shown. How does Mendix determine where to show the pop up and can this in any way be influenced?