Everyone knows this scenario: You want to open a file in the File Browser Dialog but the filter is set for a variety of filetypes (e.g. all image formats) but you only want to see the JPEG-Images.
Here is the solution: type (without the quotes) "*.jpg" into "Filename" textbox and hit "Enter". Done!
Explanation: the "*" stands for any name so you want to filter any file name with the file type ".jpg".