Bug 219901 [Undo] new file creation subjec to Undo (file deleted without warning)
when creating a new file by right clicking on your project in the project explorer new->file this action is put on the undo/redo stack. Pressing Ctrl-Z to undo this action will thus delete your file. As this stack is separate from the stack in the editor , one can create a new file, work for a long time, then inadvertently press ctrl-z to undo a code change while having the focus on the project explorer and irrevocably lose their file. Redo will create a new EMPTY file; the work is gone, forever. This appears to only work for the "new file", not for "new->source file" etc. Although some may perceive this as a feature, it is hard to imagine a scenario where ctrl-z should permanently delete a file without warning.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/WizardNewFolderMainPage.java
protected boolean validatePage() {
		boolean valid = true;
		if (!resourceGroup.areAllValuesValid()) {
			
			if (resourceGroup.getProblemType() == ResourceAndContainerGroup.PROBLEM_RESOURCE_EMPTY
					|| resourceGroup.getProblemType() == ResourceAndContainerGroup.PROBLEM_CONTAINER_EMPTY) {
				setMessage(resourceGroup.getProblemMessage());
				setErrorMessage(null);
			} else {
				setErrorMessage(resourceGroup.getProblemMessage());
			}
			valid = false;
		}
		IStatus linkedResourceStatus = null;
		if (valid) {
			linkedResourceStatus = validateLinkedResource();
			if (linkedResourceStatus.getSeverity() == IStatus.ERROR) {
				valid = false;
			}
		}
		
		if (valid
				&& (linkedResourceStatus == null || linkedResourceStatus.isOK())) {
			setMessage(null);
			setErrorMessage(null);
		}
		return valid;
	}
}