In the Tab menu, you can choose between View as Grid and View as List. In Grid mode, the tools are laid out in a rectangular array. In List mode, they are lined up vertically, with each row showing the tool name, tool icon, and an “eye” icon if the tool is currently visible in the Toolbox.

The most basic thing you can do is to select a tool by clicking on its icon: this has the same effect as clicking on an icon in the Toolbox. You can do this in either List or Grid mode: the other functions of the dialog are available only in List mode.

The most important function of the Tools dialog is to let you choose which tools to make visible in the Toolbox, by toggling the “eye” icons that appear on the left side of each row in List mode. In particular, if you use the Color tools a lot, you may benefit from toggling visibility on for them here.

You can also change the order of tools in the Toolbox, by clicking on an item in the Tools dialog, in List mode, and dragging it up or down in the list. If you screw things up, you can always press the "Reset" button at the bottom of the dialog, to restore the defaults for order and visibility.

Right-clicking inside the dialog produces the Tools menu, which gives you an alternative way of toggling visibility or restoring the defaults.