Adjusting Size of Icons on Mac Desktop

Ever since I got my Magic Trackpad for my Macintosh, I have enjoyed using it very much; however, there is one thing that keeps happening on occasion that bugs me.  Somehow when I am trying to move icons around on my desktop I am accidentally changing the appearance of the icons on my desktop.

Normally the icons are of a size that I can see on my large display, but when I hold down three fingers to drag an icon, somehow I reduce the size of the icons on the desktop.  I have not figured out what sequence of finger movements or keys that I might be holding down that causes this.

In order to restore the icons to the viewable state that I like, I have to remember the following steps:

Click on the desktop.

Select 'Show View Options' from the 'View' menubar in the Finder.

The View Options Window should appear on the desktop and I merely adjust the slider underneath 'Icon Size'.  Back to the larger size icon for easier viewing!