Created attachment 701 [details] test case The attached HTML displays in ClawsMail without scroll bars, so if the window is too small to display the content you cannot scroll down to the bottom of the page. HTML has been validated with the w3c validator. It displays correctly in Fierfox and Thunderbird (i.e. with scroll bars). I have played around with the style sheet and have come to the conclusion that the HTML viewer has a problem with "position:absolute" of the content, left, and right styles in my example. This can be tested as follows: stick the whole text in the left <div> so you have only one long column, which will also show without scroll bars. Comment out "position:absolute" in the content and left style. Now you will get scroll bars.
the gtkhtml2 plugin has now been dropped and superseded by the Fancy plugin