Extjs4 message box removes the close button (similar to Ext.Msg.alert)_extjs

The effect is as shown in the figure, similar to Ext.Msg.alert(); but there is no close button

Due to the close button in the Extjs4 message box, the callback function is not executed. After clicking the close button, the window is closed directly.
The implementation code is as follows:

Copy code The code is as follows:

Ext.Msg.show({
title : 'System prompt',
msg : 'Extjs4 removes the close button in the upper right corner of the prompt box',
buttons: Ext.Msg.OK,
fn: showResult,
closable: false
});