给ModalPanel添加属性
onbeforeshow="removeTabHandlingFromPanel(jQuery('[id$=panelId]').get(0).component);"
removeTabHandlingFormPanel()内部如下
function removeTabHandlingFromPanel(modalPanelComponent){
modalPanelComponent.lastOnfocus = function(event){};
modalPanelComponent.firstOnfocus = function(event){};
modalPanelComponent.processAllFocusElements = function(event){};
modalPanelComponent.processTabindexes = function(event){};
modalPanelComponent.restoreTabindexes = function(event){};
modalPanelComponent.preventFocus = function(event){};
modalPanelComponent.restoreFocus = function(event){};
}