I want to add a custom column to the Inbox which is a Yes/No column. I want an icon to show in the Yes case. How can I do this?
Everything I've looked up is either about adding a column through the View.XML property, through UserProperties.Add with addToFolderFields = true, or through Field Chooser.
There are also a lot of forums where Dmitry from dimastr.com just tells people it's not possible to set an icon with no real explanation.
It's pretty frustrating - why would Outlook's UI support creating Icon fields if you can't set an icon for them?! Won't they just always be blank columns?!
Some alternative questions that would also help if they were answered:
What is the "bitmap" element in the View.XML of a <column>?
How can I set a userproperty as the value of a column using the "prop" element of a <column>?
Where can I find a description of the View.XML definition? Microsoft articles all have bad links.
Icons in the Header and icons in the column itself aren't possible without some kind of Windows API hacks on the column cells.
If someone has a good one, I'll mark it as an answer. Otherwise, I'll mark this ("Impossible") as the accepted answer.
EDIT: I looked with Spy++. Outlook's view is a "SUPERGRID" that is manually painted. You don't have access to individual cells. So that makes it a lot harder. A hack would have to like subclass the SUPERGRID and override some internal method or something. Then replace Outlook's SUPERGRID with the subclassed one. Or something equally terrible. I'm thinking impossible is the only real answer...