Hello Vincent, > So you wanna join the game? ;-)
Well, sometimes it's hard to resist :-) >> Normally you would assume that if you define a position wrt a >> certain area (i.c. the page viewport), percentages are also >> interpreted wrt to width and height of that same area. > The added remark to the "left" property (7.6.5) states that it > should be "interpreted in the prevailing coordinate system > (established by the nearest ancestor reference area)". You're right, and that would rule out the page viewport. Still I'd like to think (and hope) that they simply forgot to add "...or, if absolute-position has the value 'fixed', the page-viewport area" here. The sections quoted below, when taken together, state that for fixed areas, "left", "top" etc. should be interpreted immediately as relative to the page-viewport: 4.2.2 Common Traits (...) Each area has the traits top-position, bottom-position left-position, and right-position which represent the distance from the edges of its content-rectangle to the like-named edges of the nearest ancestor reference-area (or the page-viewport-area in the case of areas generated by descendants of formatting objects whose absolute- position is fixed); 4.9.1 Geometry (...) All areas in the tree with an area-class of xsl-fixed are positioned such that the left-, right-, top-, and bottom-edges of its content- rectangle are offset inward from the content-rectangle of its ancestor page-viewport-area by distances specified by the left- position, right-position, top-position, and bottom-position traits, respectively. 5.5.4 Absolute-position Property If absolute-position has the value "absolute" or "fixed", the values of the left-position, top-position, etc. traits are copied directly from the values of the "left", "top", etc. properties. Otherwise these traits' values are left undefined during refinement and determined during composition. So, at the moment, it seems that we can all take our pick depending on what we prefer. Time for official clarification indeed. Personally I hope that: a) percentages and explicit lengths should always be interpreted in the same coordinate system, and b) for absolute and fixed areas, that this coordinate system is always the ancestor which the area is "attached to" (nearest ancestor-ref and page-vp, respectively). Kind regards, Paul Vinkenoog
