Re: [css3-multicol] test suite

Also sprach fantasai:

 > >    <div class=height-constrained-multicol>....<img class=tall>  ....</div>

 > I have a strong opinion on how things should behave in the non-balancing
 > case, specifically, that column boxes should be as high as the multicol box's
 > height and the rules should be drawn accordingly.

Ok.

 > I have less of an opinion
 > on the balancing case. You might want to draw the rules at the balance height,
 > whether that height is overflowing the box or not. You might want to do that,
 > but make the rules a minimum of the multicol box height. Or you might want to
 > make the rules always be the multicol box height.

Personally, I'm leaning to the last option. That seems simpler, and it
seems natural for column rules to end where the background color ends.
But it's clipping, and if we clip rules at the content edge, we should
also do so for very wide rules and rules that fall entirely outside
the multicol box.

Let's try to list the different conditions when clipping column rules
may be desireable:

a) a colspan element crosses the rule

b) an unsplitable element (say image) inside the multicol element
   creates an overflow condition, and 'column-fill: balance'

c) an unsplitable element (say image) inside the multicol element
   creates an overflow condition, and 'column-fill: auto'

d) the column rules are wide and extend outside the multicol box

e) the multicol box has constrained height and, therefore, extra
   columns -- with rules? -- are created outside of the multicol box.

Further, we have a condition when it may be argued that column rules
should be shorter than the multicol element:

f) the multicol element is higher than the natural height of balanced
   columns.

Of these, I think we all agree that column rules should be clipped in
a). Also, I think we agree (at least, I agree with Robert) that column
rules should be kept to the natural height in f).

In b-e, we have the following positions:

  b) Håkon favors clipping, Fantasai has no strong opinion, Robert favors showing
     
  c) Fantasai/Håkon favor clipping, Robert favors showing

  d) Håkon favors clipping, Robert (and Fantasai?) favor showing

  e) Håkon favors clipping. Fantasai/Robert favor showing

Hmm. Perhaps it's better to find a resolution by looking at pictures. 

Consider the attached image. The red box is a tall image that sticks
out, outside the multicol element. The column rules are in lime. The
multicol element has a yellow background and a blue border.

Example 1 is the "show-all" option. Example 2 is a middle alternative:
clipping is done vertically, but not horizontally. Example 3 is the
"clip-to-multicol-box" position.

Hmm. Perhaps Example 2 looks the best?

-h&kon
              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome