Style popup menu

Version v3.0.5 introduced experimental types of link visualisation that can be set per-link. These settings override global settings made via the Preferences' Curved Links option. The choices offered are:

• normal. Use the inherited value. This style is not a style per se but rather it corresponds to the default or inherited color.
• linear. Link is shown as a straight line.
• curved. Link is shown as a curved line.
• bold linear. Link is shown as a bolded straight line.
• bold curved. Link is shown as a bolded curved line.

This menu is added as a pop-up to both the Create Link and Browse Links dialogs.