WPF 15 extra pixels in Window display

Question

I come from a WinForms background, so WPF is foreign to me. I am experimenting with it and trying to make a simple Hello World! application, except that the application displays different at runtime than how it is in the designer.

What I mean by that is I have a 'Hello!', and in the designer the location of the button is 12, 12, and and the Window is sized so that is the right/bottom edge of the button is 12, 12 pixels from the right/bottom edges of the window (so there is uniform 12 pixels around the button). When I run the application the button is still 12, 12 pixels from the top & left edges, but is 27, 27 pixels from the right/bottom edges of the Window. I have verified that the button dimensions are correct (I took a screenshot and measured the button in Adobe Photoshop and verified that the button width & height in the XAML code was the same as what was displaying on the screen). The Window is what is growing bigger.

I also verified it was not the canvas getting bigger by explicitly setting the width & height, changing the background color, and setting horizontal/vertical alignment to left/top. So when I ran it again, the canvas stayed the same size, but the Window still had an extra 15 pixels on the right/bottom.

I have tried Googling & searching here for this problem, but can't find an explanation as to why runtime is different from the designer.

I should note I am using Visual 2010, and I am using a simple for the layout.

Anyway, thanks for any clues as to why I am getting 15 extra pixels.

(Note I'd post a screenshot, but as a new user I'm not allowed).

Answer 1

You can use a tool like Snoop to diagnose this. It should allow you to inspect the entire visual tree of your application, and determine which UIElement is responsible for the extra pixels.