Bug 104986 Backgound image uses an absolute path
Currently Chart uses an absolute path to indicate a backgournd image, that may cause the design unusable on other environments. Expected the background image can be definded in multiple ways like in report designer. e.g. URI(absolute path), File(relative path), Embedded Image(Encoded Image Data).
chart/org.eclipse.birt.chart.ui.extension/src/org/eclipse/birt/chart/ui/swt/composites/FillChooserComposite.java
glButtons.marginWidth = 4;
		glButtons.horizontalSpacing = 1;
		glButtons.verticalSpacing = 4;
		glButtons.numColumns = 2;
		cmpButtons.setLayout( glButtons );
		GridData gdButtons = new GridData( GridData.FILL_HORIZONTAL );
		gdButtons.horizontalSpan = 8;
		cmpButtons.setLayoutData( gdButtons );
		cmpButtons.addKeyListener( this );
		
		GridLayout glTransparency = new GridLayout( );
		glTransparency.numColumns = 1;
		glTransparency.horizontalSpacing = 5;
		glTransparency.verticalSpacing = 3;
		glTransparency.marginHeight = 4;
		glTransparency.marginWidth = 0;
		Composite cmpTransparency = new Composite( cmpButtons, SWT.NONE
				| SWT.NO_FOCUS );
		GridData gdTransparency = new GridData( GridData.FILL_BOTH );
		gdTransparency.horizontalSpan = 2;
		cmpTransparency.setLayoutData( gdTransparency );
		cmpTransparency.setLayout( glTransparency );
		lblTransparency = new Label( cmpTransparency, SWT.NONE );
		GridData gdLBLTransparency = new GridData( GridData.FILL_HORIZONTAL );
		gdLBLTransparency.horizontalIndent = 2;
		lblTransparency.setLayoutData( gdLBLTransparency );
		lblTransparency.setText( Messages.getString( "FillChooserComposite.Lbl.Opacity" ) ); 
		srTransparency = new Slider( cmpTransparency, SWT.HORIZONTAL
				| SWT.NO_FOCUS );
		GridData gdTransparent = new GridData( GridData.VERTICAL_ALIGN_BEGINNING