The height of a free-sized RadPane is not calculated properly on layout mode change in Android devices. The issue is reproducible in Firefox for Android.
Firefox for Android is not included in the list of mobile browsers supported: http://www.telerik.com/aspnet-ajax/tech-sheets/browser-support Its popularity is less than 1% of all mobile browsers usage share - in many statistics it falls into the “Others” category: http://gs.statcounter.com/#mobile_browser-ww-monthly-201401-201405 , https://www.netmarketshare.com/browser-market-share.aspx?qprid=0&qpcustomd=1