[css-exclusions-1] Is the CSS exclusions processing model incorrect?

[svgeesus]

from the old bugzilla, originally raised by in 2011 @dbaron

Feedback from David Baron:

November TPAC meeting: http://lists.w3.org/Archives/Public/www-style/2011Nov/0714.html

Email from David: https://lists.w3.org/Archives/Member/w3c-css-wg/2011OctDec/0371.html

Action Item for David to provide description of the problem for insertion in the spec:

https://www.w3.org/Style/CSS/Tracker/actions/415

[svgeesus]

response from Rossen

(Issue description from DBaron's ACTION-415)

These rules for exclusions order and exclusions on absolutely positioned elements (particularly those with static position) build this exclusions model on top of the absolute positioning model in CSS Level 2, rather than on top of floats, the existing exclusion model in CSS Level 1 and 2. The CSS Working Group has not reached consensus on whether it intends to base the new exclusions features in this specification on top of absolute positioning (as these sections of this specification do) or on top of floats.

[svgeesus]

response from @astearns

Changed issue description:

The current draft provides a model for exclusions
without a collision-avoidance model. The existing
exclusion model in CSS uses floats, which have both
exclusion and collision-avoidance behavior. Concerns
have been raised that allowing exclusions without
collision avoidance could be harmful, particularly
with absolutely-positioned elements. Three options
should be considered:

1. Allow exclusions in positioning schemes with no
   collision avoidance
2. Disallow exclusions in positioning schemes with
   no collision avoidance
3. Define collision-avoidance behavior for positioning
   schemes without it, and use this behavior by default
   with exclusions.

https://dvcs.w3.org/hg/csswg/rev/d238b1e9c4ac