When the "Auto Image Size" option (options > view) is set to fit window to image or fit image to desktop, the window size changes when you open an image. If the Browser mode is set to display a toolbar and the image viewing mode is set not to display a toolbar (or if the viewer does and the browser does not), then when returning to the Browser from the image, XnView does not resize itself back to normal like it's supposed to, but rather remains at the size it was when viewing the image.
This also occurs when the image's width is below the minimum required to display the entire menu bar. XnView sizes down to the point that the X button to close the current image wraps around to a second line, and i speculate that it's this change in height of the viewing area that causes the same problem as the one encountered when the toolbar settings don't match. I can get a screenshot of this situation if you'd like.
I'm using Windows 7 x64, window border padding set to 0, border width 1, title bar width 18.
Browser sometimes doesn't resize back to normal
Moderators: helmut, XnTriq, xnview