The text dialog is a tool to define text settings for the active selector/class in the active stylesheet.
Most of the stuff is self explanatory. Any old commands for text color or justification can be removed by clicking the "delete cross".
Beware that settings can be event driven. For instance links can look different depending on the action. Links are usually underlined (default), but this can be changed by setting the Text Decoration property to "none". If you want the link to be underlined when the mouse passes over, set the "Hover" selector to Text Decoration = underlined.