View source for E4/EAS/Undo Redo

Components should be able to isolate their own atomic operations for supporting undo/redo. These should be connected to the base platform in some way to ensure that when a user invokes undo/redo, the context of the application can be analyzed and the right operation stack can be processed for undoing/redoing.

==Eclipse 3.x API==
In Eclipse 3.x, the IWorkbenchOperationSupport interface provided by PlatformUI.getWorkbench().getOperationSupport() can be used for managing undo/redo support.

===Execution operation===
<source lang="java">
IWorkbenchOperationSupport operationSupport = PlatformUI.getWorkbench().getOperationSupport();
IOperationHistory operationHistory = operationSupport.getOperationHistory();
IStatus status = operationHistory.execute(undoableOperation, null, null);
if (!status.isOK()) {
  // handle the error
}
</source>

===Undo operation===
<source lang="java">
IWorkbenchOperationSupport operationSupport = PlatformUI.getWorkbench().getOperationSupport();
IOperationHistory operationHistory = operationSupport.getOperationHistory();
IStatus status = operationHistory.undo(undoableOperation, null, null);
if (!status.isOK()) {
  // handle the error
}
</source>

===Redo operation===
<source lang="java">
IWorkbenchOperationSupport operationSupport = PlatformUI.getWorkbench().getOperationSupport();
IOperationHistory operationHistory = operationSupport.getOperationHistory();
IStatus status = operationHistory.redo(undoableOperation, null, null);
if (!status.isOK()) {
  // handle the error
}
</source>