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/WizardNewFileCreationPage.java
* Set the only file extension allowed for this page's file name field.
	 * If this page's controls do not exist yet, store it for future use.
	 * <br><br>
	 * If a file extension is specified, then it will always be 
	 * appended with a '.' to the text from the file name field for 
	 * validation when the following conditions are met:
	 * <br><br>
	 * (1) File extension length is greater than 0
	 * <br>
	 * (2) File name field text length is greater than 0
	 * <br>
	 * (3) File name field text does not already end with a '.' and the file 
	 *     extension specified (case sensitive)
	 * <br><br>
	 * The file extension will not be reflected in the actual file
	 * name field until the file name field loses focus.
	 * 
	 * @param value
	 *             The file extension without the '.' prefix 
	 *             (e.g. 'java', 'xml') 
	 * @since 3.3
	 */
	public void setFileExtension(String value) {
		if (resourceGroup == null) {
			initialFileExtension = value;
		} else {
			resourceGroup.setResourceExtension(value);
		}
	}