Webview height is not being update?

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http://stackoverflow.com – I am working on a HTML book reader so in web-view i am loading the webpages .Here i am having zoom in and zoom-out buttons so on clicking of zoom-in i am increasing the web view parameters i.e Width and Height but my problem is that after changing the params the height parameters is not updates that meaning it do not comes to the new given height .Specially in case of zoom out it show the previous height itself but width works OK and content also shrink.It will not update the height until any click event happens if i click on some buttons or moves to the next page it comes p (HowTos)