Presentation tweak to avoid graphical glitch

Hovering the right end of an email title in the popup window could cause graphical flickering, since the mouse-over event changed the title text to italic, which in general was more narrow than regular text, causing the mouse pointer to no longer be "over" the title. This in turn immediately triggered the title change to regular text, which once again caused the mouse to be over the title, and so on until the pointer was moved away.

Reducing the base title emphasis from bold+underlined to just bold allows mouse-over to be clearly signaled by underlining instead of italics, avoiding the issue. This is also how the action labels below the title are already handled.

This brings the emphasis down to the same level as the "From:" label, which does not need to be that prominent, so bold is removed and it is grayed out to some extent.

It could be a nice addition to add a visual cue to when the user has pressed on a title to load the fulltext, e.g. by appending an ellipsis, or using the now available italic emphasis for this, but that is not in this pull request.