Compatibility with Shoes 3

Shoes 4 strives to be as fully compatible with Shoes 3 as possible, but occasionally pragmatic decisions needed to be made to get things to 🚢

This page lists known differences from Shoes 3 to keep in mind as you upgrade applications:

• video element is not supported. (See #113 for issue to fix it in future Shoes)
• Font sizes and gaps are smaller in Shoes 4. This may require revision in apps that did precise positioning.
• Block-form image calls are not supported. (See #1309 for further discussion and future work on supporting that)
• Widgets must define initialize_widget instead of initialize. This may require code changes in applications, but a detailed warning is given when we detect the situation.