Adrian, just curious, why would you want to do that
deliberately? I mean, selecting the
whole page.
As to getting Marvin's menu buttons to pop up, just tap and hold any word on the screen. You can then expand the selection of the highlighted word either by dragging the right and left selection markers as usual in iOS, or by using Marvin's unique
+Word and
Extend buttons.
The behaviour you describe is actually (in all likelihood) a UIWebView bug that makes proper highlighting (such as across paragraphs, or across screens) impossible in Marvin and other apps, not only e-readers but also the default Safari browser. (See the discussion, earlier in this thread, of "paragraph snapping" when selecting text on iOS devices.)