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
if(report.canDropCssStyleSheet( cssStyleHandle ))
			{
				report.dropCss( cssStyleHandle );
			}
		}else
		if(containerHandle instanceof ThemeHandle)
		{
			ThemeHandle theme = (ThemeHandle)containerHandle;
			if(theme.canDropCssStyleSheet( cssStyleHandle ))
			{
				theme.dropCss( cssStyleHandle );
			}
		}
		
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.gef.commands.Command#canExecute()
	 */
	public boolean canExecute( )
	{
		return canDrop( model );
	}
	/**
	 * Returns the object can be deleted. If the parent can be deleted, the
	 * children will be skippedl
	 * 
	 * @param source
	 *            single or multiple objects