Some MediaPanels in tabpanel.
With MediaPanel display PDF files.Each tag is a PDF.
But after the completion of the loading all PDF,I Switch the tags.
Some MediaPanels appear white screen.
Why???

var pdf_2 = new Ext.ux.MediaPanel({
id: 'pdf_2',
renderTo: document.body, //Ext.getBody(),
LoadMask: true,
border: false,
maximizable: true,
mediaCfg: {
mediaType: 'PDF'
, url: m_web_service + m_url1
, unsupportedText: 'No installation PDF'
},
mediaMask: true
});