The start panel uses 32px icons for the programs list on the left but 24px icons for the places list on the right. --- Any icons that are used in the start panel should include those sizes in order to display properly. Otherwise they will be resized to fit.
Standard image sizes included in an icon file are 256, 96, 48, 32 and 16. --- Image sizes 128, 96 and 24 are not standard and you will have to select them in your icon program if you want them included.
