Position and Size
Indicate where you want the upper left corner of the new window to be placed on the screen. You can also indicate the width and height of the window.
These settings are measured in pixels by default. You can
specify relative values by following the number with a % sign.
For example, specifying a width of 50% will make the new window half
the size of the available screen width.
You may also leave any of these settings empty (blank) so the
new window is created with the client's default values.
Select the "Center on screen" option if you want to have the
dialog appear centered on the screen regardless of the screen size
(resolution).
Note that no verification will be done, so if the position places
the window outside the visible area of the user's screen, the window will not be seen.