In Photoshop we can easily increase/decrease any values by using arrow keys or dragging left/right after hovering mouse on the subject. But I found neither is possible in Fireworks CS6. Am I missing something?
Do you mean values such as border radius and stroke? Or values such as brush size? Or both?
There are countless amounts of useful extensions that may be able to help, such as these http://fireworks.abeall.com/extensions/