ConwayLife.com

I think I've narrowed this down, such that every step below is necessary to observe the bug, at least for 2.6 on Windows 7 64-bit, (and I don't see anything of this nature listed on the sourceforge page under changes in version 2.7).

Step 1: open a pattern from clipboard using Ctrl+Shift+O
Step 2: change to a toroidal grid smaller than the pattern (it will say "Pattern was truncated")
Step 3: press enter to run the pattern
Step 4: press Z to return to generation zero

Observe the population now reads that from before truncation, but the displayed pattern is still on the torus. Running the pattern again does not give the correct behavior, due to ghost cells beyond the edge of the visible grid. You can select all and delete and still have a nonzero population and births into the visible grid on generation 1.

This only happens when the initial pattern is opened from clipboard.

Interesting. You can also hit rewind instead pf z

interestingly enough, the same bug does not occur in my outdated copy of Golly 2.5 for Mac. When I tried to reproduce it, it returned to gen 0 and changed the rule back to the infinite grid size.

biggiemac wrote:I think I've narrowed this down, such that every step below is necessary to observe the bug...

Thanks for the excellent bug report. I've fixed the problem in version 2.8 (hopefully released this year!).