Bug 182076 Delete a style from a report item doesn't affect report xml source
Steps to reproduce: 1.Insert a label onto layout; 2.New a style, suppose named it "NewStyle"; 3.Right click the label and on the drop down list, choose Style->Apply Style->NewStyle; 4.Save the report design; 5.Right click the label and on the drop down list, choose Style->Delete Style->NewStyle; 6.Save the report design; Expected result: NewStyle is deleted from report design, and the label doesn't have the style property. Actual result: Switch to report xml source, a error mark indicate that the label still has a style property:<property name="style">NewStyle</property>
UI/org.eclipse.birt.report.designer.core/src/org/eclipse/birt/report/designer/core/commands/DeleteCommand.java
return false;
		}
		source = DNDUtil.unwrapToModel( source );
		if ( source instanceof SlotHandle )
		{
			SlotHandle slot = (SlotHandle) source;
			DesignElementHandle handle = slot.getElementHandle( );
			return slot.getContents( ).size( ) > 0
					&& ( ( handle instanceof ListHandle && ( (ListHandle) handle ).canDrop( ) ) || ( handle instanceof ListGroupHandle && ( (ListGroupHandle) handle ).canDrop( ) ) )
					&& canDrop( slot.getContents( ) );
		}
		if ( source instanceof EmbeddedImageHandle )
		{
			return true;
		}
		if ( source instanceof CellHandle )
		{
			
			return ( (CellHandle) source ).getContent( ).getContents( ).size( ) > 0
					&& ( (CellHandle) source ).canDrop( );
		}
		if ( source instanceof MasterPageHandle )
		{
			if ( SessionHandleAdapter.getInstance( )
					.getReportDesignHandle( )
					.getMasterPages( )
					.getCount( ) > 1 )
			{
				return true;
			}