Internet Explorer 8 compatibility issues

Using GWT, I had an issue with pop up panels not showing content in IE8 so in order to force the compatibility mode in IE8 to turn on, I added this html script which you have to put inside a meta tag:

equiv="X-UA-Compatible" content="IE=EmulateIE7"

Also another issue with GWT/IE is that in the html we assign class="hidden" to our page, but in order to make our page visible again we can't use:
RootPanel.get("page").addStyleName("visible");

We must use the code below for IE:
RootPanel.get("page").getElement().getStyle().setProperty("visibility", "visible");