Using the mouse

Scroll

Hold down the ALT-key while you press down your left mouse button at the same time to scroll.

Note: Pressing down the space bar has the same effect as using the ALT-key, but this works only when the cursor is hidden.

Zoom

Keep the CTRL-key pressed down and use the scroll wheel of your mouse to zoom in out.

Choose color / symbol

Click with your middle mouse button on a grid square to select its color of symbol, so you use it for drawing.

Select tool

Hold down the SHIFT-key and hold down your left mouse button to make a selection.