Hi Abdul,
Unfortunately Resize to fill does not work with vertical images as the top and bottom are cut off. Horizontal images are fine, although the ugly shadow is still slightly visible.
It would be a lot better if there was an option to align gallery images left, centre or right in Re-size to fit and only show the image, not all the horrible surround shadow, so you just flick through the images without seeing the surround.
I have deleted the gallery sections and am using thumbnails instead, perhaps Stackideas could look at the gallery output and imporve it in a future update?
Also the thumbnail sequence in the pop up view goes down column 1, then down column 2 etc, it should go across row 1 (left to right), then across row 2 (left to right) etc, with an option to go right to left available, as when setting up the thumbnails, this is the sequence used (the output sequence should be the same).