Move to next text flow when tab key is pressed

[velara3]

When tab key is pressed in a text flow and manageTabKey is enabled we move the cursor to the next text flow.

[velara3]

This behavior has been added in the last commit.

Questions:

1. Should this behavior be enabled when manageTabKey is enabled or disabled? Currently manageTabKey has meant TLF should pay attention to the tab key and prevents the Flash Player from handling it. Or should there be another property to handle this, ie, moveToNextCellOnTab?
2. Will this conflict with tab behavior of the text flow in the table cell? For example, if a list is in a table cell text flow how do we want to handle this? In InDesign lists are only one level deep. Tab moves to the next cell.
3. Currently when we tab to the next text flow we highlight the text flow contents. Should we highlight it or set the cursor at the end of the text flow? Code is there for both behavior types. In InDesign when a tab is pressed the text is highlighted in the destination text cell (which is the current behavior). Should we make this an option?