Bug 176681 Issue about creating context-parameter path in read-only path[0601]
Description: Issue about creating context-parameter path in read-only path Build number:2.2.0.v20070308 Steps to reproduce: 1. Deploy birt. 2. Set BIRT_VIEWER_DOCUMENT_FOLDER/BIRT_VIEWER_IMAGE_DIR/.. to a read-only path. 3. Preview report. Expected result: Because the path is read-only, folders should be created in ${java.io.tmpdir} Actual result: No folders are created in ${java.io.tmpdir} and reports cannot be previewed in frameset mode.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
/**
	 * URL parameter name that specifies the viewer id.
	 */
	public static final String PARAM_ID = "__id"; 
	/**
	 * URL parameter name that specifies the report title.
	 */
	public static final String PARAM_TITLE = "__title"; 
	/**
	 * URL parameter name that specifies whether show the report title.
	 */
	public static final String PARAM_SHOW_TITLE = "__showtitle"; 
	/**
	 * URL parameter name that specifies whether show the toolbar.
	 */
	public static final String PARAM_TOOLBAR = "__toolbar"; 
	/**
	 * URL parameter name that specifies whether show the navigationbar.
	 */
	public static final String PARAM_NAVIGATIONBAR = "__navigationbar"; 
	/**
	 * URL parameter name that specifies whether force prompting the parameter
	 * dialog.
	 */
	public static final String PARAM_PARAMETER_PAGE = "__parameterpage"; 
	/**
	 * URL parameter name that gives the report design name.
	 */
	public static final String PARAM_REPORT = "__report"; 
	/**