# Adopting 4.2 mechanisms and APIs

This section describes changes that are required if you are trying to change your 3.7 plug-in to adopt the 4.2 mechanisms and APIs.

1. New member flag IContainer#DO_NOT_CHECK_EXISTENCE
2. Large icons in product branding
3. CTabFolder top right control layout

## 1. New member flag IContainer#DO_NOT_CHECK_EXISTENCE

The new flag may be used in:

- IResource#accept(IResourceProxyVisitor, int)
- IResource#accept(IResourceVisitor, int, int)

to indicate whether the resource should be checked for existence. If the flag is not specified (recommended) and the resource does not exist, CoreException will be thrown. Children of the resource are never checked for existence.

## 2. Large icons in product branding

The Eclipse executable on Windows now includes a larger 256x256 icon image. If you are using a PDE product build or the p2 publisher to apply branding for your own product, you will now need to include a 256x256 image in the .ico file you specify for your product or build. Note that the p2 branding tool does not support compressed PNG images, so currently all of your branding images must be uncompressed bitmaps.

## 3. CTabFolder top right control layout

If a top right control will not fit in the available tab space, CTabFolder will automatically wrap it when the control is set with the SWT.WRAP alignment flag. Any layout code that was handling control wrapping for CTabFolders should be removed in favor of the SWT.WRAP. For more info, see CTabFolder#setTopRight(Control control, int alignment).