Tool Bar

The Alchemy tool bar is used to control how shapes look when they are created. For example, you can change the style of the shape, the transparency, the line width and so on. When it is attached to the main window, the tool bar can be toggled on and off by pressing the space bar.

Let's go through the controls on the tool bar one by one.

Style

Toggle between drawing with a line or solid fill.
Keyboard Shortcut: S

Over/Under

Toggle between drawing over other shapes on the canvas or under them.
Keyboard Shortcut: D

Line Weight

Increase/Decrease the line weight.
Keyboard Shortcut: [ ]

Colour

Set the colour of the foreground or background. Firstly select either foreground or background, then click on the colour button to bring up this colour picker:

Click on an area inside the colour picker to choose a colour. The area at the top of the colour has black,  grey (50%), and white. Use the button with three dots (...) to open a more precise colour chooser window.

Foreground/Background

Select either the foreground or background colour to draw with. You can use the colour picker to change either of these colours.
Keyboard Shortcut: X

Transparency

Adjust the transparency of the foreground colour. The background colour is always opaque.

Create & Affect

These two buttons control the currently selected Alchemy 'module', and also the controls that appear in the bottom part of the tool bar.

Clear

Clear the entire Alchemy canvas.
Keyboard Shortcut OS X: Command + Backspace
Keyboard Shortcut Windows: Ctrl + Backspace