For those of you that are diligently testing the bounds of the web, you may have noticed some issues when debugging GWT apps within Internet Explorer 9. Even though IE 9 is still in a pre-release phase, we did want to provide some context around the root of the problem, and offer up a workaround to get you working in Development Mode again.
Note that this is only an issue when running your GWT app in Development Mode under IE 9. Production Mode is unaffected.
For some background, there appears to have been a change in behavior in IE 9 related to the way Javascript names are resolved from the perspective of native plugins. When executing in document mode 9, the IE tab that hosts the dev mode plugin crashes.
We are working with Microsoft to understand the issue and come up with a definitive solution. Again, note that this issue affects only GWT Development Mode.
Workaround
The current workaround is to avoid document mode 9. See the link below for more information.
To force an earlier document mode, add a meta tag to your html files indicating a different document mode. For instance, in the case of the sample GWT app html page, add <meta http-equiv="X-UA-Compatible" content="IE=8" /> to the <head> section as shown below:
<!doctype html>
<!-- The DOCTYPE declaration above will set the -->
<!-- browser's rendering engine into -->
<!-- "Standards Mode". Replacing this declaration -->
<!-- with a "Quirks Mode" doctype may lead to some -->
<!-- differences in layout. -->
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=8" />
Until this issue is resolved, you will need to do this for each HTML host page in order to use GWT dev mode with IE9.
References
MSDN - Defining Document Compatibility
