Proposal: Update TabView to use ItemsRepeater

[stmoy]

Proposal: Update TabView to use ItemsRepeater

Summary

Currently, TabView uses a ListView "under the covers" for the tab strip area. This limits our ability to implement features like drag-and-drop rails and improved animations. This proposal suggests updating TabView to use ItemsRepeater "under the covers" instead, which would enable us to implement drag and drop, animations.

Rationale

The TabView vNext issue #1332 proposes improvements to features such as drag and drop and animations. The current TabView implementation uses ListView "under the covers" which provides these services as part of ListViewBase. This, in turn, makes it very tricky to implement improvements to TabView because they would potentially also affect ListViewBase (which would affect ListView, GridView, NavigationView, TreeView...)

TabView was originally built in a way that obfuscates the fact that it uses a ListView as an implementation detail because we knew we might want to update to ItemsRepeater instead.

• Unblocks us from implementing improved drag and drop and improved animations
• Provides more validation on ItemsRepeater

Scope

Capability	Priority
This proposal will allow developers to accomplish W	Must
This proposal will allow end users to accomplish X	Should
This proposal will allow developers to accomplish Y	Could
This proposal will allow end users to accomplish Z	Won't

Important Notes

Open Questions