On 05/15/2011 11:35 AM, Steffen Wolfrum wrote:

Hi Hans,

while finishing a big project (900 pages, 300 floating tables/figures) I noticed that the first line of each page is moving up/down (almost half a line)!

Reason: As soon a a floating object is placed the next page is disturbed.

The problem is that the vertical space collapser is collapsing *into*
topskip's spec field, thereby changing its value. That much is
clear to me. I do not know how to fix this nicely, but a crude
workaround to fix your project is:

\appendtoks \global\topskip=10pt plus 50pt \to \everyafteroutput