Here are some helpful hints on common tasks:
You can open a browser on any system construct from almost any other browser by clicking on the folder tab and entering the name (you can just enter a prefix of the name, or use # or * as wildcards). If the name appears in text, you can click on it and type <Ctrl>O or bring up the context menu, and select "Smalltalk/Open Definition" to open a browser on it.
To create a new class, open its superclass, and select "Browse/Add subclass ...".
To add a category, select "New Category" from the context menu for either the "Instance side" or "Class Side" entries.
To add a method to a category, select "New method" from the context menu for the category.
When editing text, you can accept the text without using the context menu by typing <Ctrl>-<Enter> (or just <Enter> for single line text fields like the category name).
You can browse the senders, implementers, and messages of a method using the context menu for the method header.
You can turn auto-indent on or off from any text view context menu.
The normal windows cut/copy/paste keys work (Ctrl-X,Ctrl-C, and Ctrl-V, respectively)