Bug 102150 RCP splashscreen stays forever in case of error
If a serious error occurs during the startup of an RCP application, like a missing plugin etc. so that the application could not start, the splash screen of the application stays for ever. This happens if the application is started by PDE using the "Run as eclipse application" menu, but the process has been stopped using the "Stop" button. I had to kill the new eclipse.exe process using the windows taskmanager.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
if (executionListener == null) {
			throw new NullPointerException(
					"Cannot remove a null execution listener"); 
		}
		if (executionListeners != null) {
			executionListeners.remove(executionListener);
			if (executionListeners.isEmpty()) {
				executionListeners = null;
			}
		}
	}
	/**
	 * <p>
	 * Removes a state from this command. This will remove the state from the
	 * active handler, if the active handler is an instance of
	 * {@link IObjectWithState}.
	 * </p>
	 * 
	 * @param stateId
	 *            The identifier of the state to remove; must not be
	 *            <code>null</code>.
	 */
	public void removeState(final String stateId) {
		if (handler instanceof IObjectWithState) {
			((IObjectWithState) handler).removeState(stateId);
		}
		super.removeState(stateId);
	}
	/**
	 * Changes the handler for this command. This will remove all the state from