If you’re tired of tapping the left and right brackets to increase / decrease your brush size, try using the new Drag-resize brush cursor keyboard shortcut in Photoshop CS4 to make rapid changes to the brush size. Ctrl + Option (Mac) / alt + right click (win) -drag will increase/decrease brush size while displaying a red overlay of the density and feather of the brush for visual reference. Add the Cmd (Mac) /shift (Win) to change hardness. Note: the preview color can be controlled in Preferences / Cursors / Brush Preview).
