How to replace icon?
 

I created a shortcut for a website and added it to my taskbar. The icon shows as the Firefox icon. I tried selecting a different icon but there was not an icon for my website. I created an icon using Gimp and copied it into the file for icons (usr/share/icons/Mint-X/apps/48) and it looks ok in the preview pane but when I try to replace the Firefox icon it goes to a default icon. I created the icon as a 48 X 48 image and exported to a png file. I am using LinuxMint 16 with the Mate desktop. I did notice that my icon was 2 or 3 times bigger than the average icon and I did not use compression when exporting it. Where did I go wrong and which log file would I find the error message in? Thank you.

Edit the shortcut with a text editor. Is your icon listed in the settings? The *.desktop files are basically INI files.

Solved
 

I created a 48 X 48 icon using Paint in XP and saved it to a jump drive. It turned out to be only 4K. I copied it into /usr/share/icons/Mint-X/apps/48 using the command line. It would not let me update the icon with the new icon until after I rebooted. The final icon turned out to be only about 750 bytes so it must have been compressed somewhere.