private void createActions() {

		toolBarAction = new NavigatableContextAction("SelectBlock", getName()) {
			@Override
			public void actionPerformed(NavigatableActionContext context) {
				showDialog(context.getComponentProvider(), context.getNavigatable());
			}

			@Override
			public boolean isEnabledForContext(ActionContext context) {
				updateNavigatable(context);
				return super.isEnabledForContext(context);
			}
		};
		MenuData menuData =
			new MenuData(new String[] { ToolConstants.MENU_SELECTION, "Bytes..." }, null,
				"Select Group 2");
		menuData.setMenuSubGroup("1");
		toolBarAction.setMenuBarData(menuData);
		toolBarAction.addToWindowWhen(NavigatableActionContext.class);

		toolBarAction.setEnabled(false);
		toolBarAction.setDescription("Allows user to select blocks of data.");
		toolBarAction.setHelpLocation(new HelpLocation("SelectBlockPlugin", "Select_Block_Help"));
		tool.addAction(toolBarAction);
	}
This plugin class contains the structure needed for the user to
select blocks of data anywhere inside of the Code Browser and Byte Viewer.
<p>
Note:  This plugin used to refer to selections as blocks instead of lengths
of bytes.  The GUI has been changed, but the internal comments and 
variable names have not.
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/select/SelectBlockPlugin.java