This samples shows how you can extend ArcObjects to build a new custom textbackground. ArcMap ships with
several textbackgrounds including: Balloon Callout, Line Callout, Marker Text Background, and Simple Line Callout.
This new textbackground is a Filled Leader Callout and it is very similar to the Balloon callout except, like its name
suggests, the leader can be filled with a symbol that differs from the balloon.
How to use:
Register the dll.
Add FilledLeaderCO.PropertyPage to the 'Text Background Property Pages' component category.
Add FilledLeaderCO.FilledLeaderCO to the 'Text Backgrounds' component category.
Add a text element onto your map.
Right-click on the selected element and select 'Properties' from the context menu.
Select 'Change Symbol'.
Select the 'Advanced Text' tab.
Click on 'Text Background', then select its related 'Properties' button.
In 'Type', select 'Filled Leader Callout'.
Its property sheet is displayed and from here you can set the leader symbol, background symbol and other properties.
Hit 'OK' on all subsequent dialogs to get back to ArcMap.