Am I correct that you are running under DotNetNuke v 5.6.2? If so, this behavior may be due to the following css rule having been added to default.css in v 5.6.2:
/* text style used for textareas in the admin and edit pages, for Nav compatibility */
textarea.NormalTextBox{width:300px;height:200px;}
Feedback.ascx uses an ASP.Net textbox control with textmode="Multiline" for it's message body field. This renders as a textarea element. In the Feedbck.ascx markup this control is given the following two css classes:
cssclass="NormalTextBox Feedback_ControlWidth"
Unfortunately the new rule defined in default.css is of higher priority causing the Feedback_ControlWidth class to be ignored. I have not tested this but your might try changing the cssclass attribute on the <asp:textbox id="txtBody" . . . /> control in DesktopModules/Feedback/Feedback.ascx to the following:
cssclass="Normal Feedback_ControlWidth"
Another fix but less likely to work might be to modify the Feedback_ControlWidth rule in DesktopModules/Feedback/module.css to the following:
.Feedback_ControlWidth
{
width: 92% !important;
}
I'm far from being a CSS expert so am not entirely sure the addition of the !important to this rule will override the textarea.NormalTextbox rule in default.css as I think the textarea.NormalTextbox rule is both more specific and will be applied later in the css cascade.
CSS experts: please offer some help here!