Under the Windows menu, there is an item named "Latex Panel..." Choosing this item will open a panel containing a large number of mathematical symbols, Greek letters, international characters, and typesetting environments. Clicking on a symbol will insert the corresponding text into your LaTeX source file. This wonderful panel is the work of Geoffroy Lenglin, who can be reached at geoffroy.lenglin@m4x.org.
Some symbols in the panel require the line
at the top of the source file.
It is possible to customize the behavior of the panel. When TeXShop first runs, it creates a file ~/Library/TeXShop/LatexPanel/completion.plist inside your personal Library folder. This file is an ordinary text file which can be opened and edited by TeXShop. The file contains all strings inserted into the source code when a Palette item is chosen. If such a string contains #SEL#, then the current selection will replace this expression in the inserted string. If a string contains #INS#, then the cursor will be set to this position when the string is inserted. To customize panel behavior, edit completion.plist.
Editing plist files is slightly tricky; see the item about them at the end of this help file. Be sure to edit and save in UTF-8 format if you use Unicode characters.
Users can add up to sixteen additional items to the Latex Panel by editing completion.plist. These are displayed on the "Custom" subpanel of the Latex Panel. See comments in completion.plist for details about adding such items.