Shortcut numbers in "Window" menu flip-flopping intermittently

I'm using Opera 11.51 build 1087 on Windows 7 SP1 x64. I run with Opera's menu bar visible and make frequent use of the numbered tab shortcuts on the Window menu. To clarify: you know how with the menu bar visible, you can use the keyboard shortcut "alt+w" followed by a number key to switch to a specific tab? I use this in a few AutoHotkey scripts to automatically switch to specific pinned tabs.

However, I've been noticing over the past few days that the numbering scheme the Window menu uses switches intermittently (sometimes as often as once every ten minutes) between the following two numbering schemes:

• "1" represents the currently active tab, followed by all tabs in order ("2" for the first tab, "3" for the second tab", etc.), so the currently active tab appears twice.
• "1" represents the first tab, "2" the second, "3" the third, etc.

Now, I don't particularly care which of these is used, because I can adjust my scripts to accommodate either way, but when it keeps changing . . . very annoying. Am I the only one who's experienced/noticed this? Maybe so, since I have a pretty specific and unusual reason to care about the numbers.

It never actually changes in front of me (i.e. while I'm looking at the Window menu), so I'm thinking it must be triggered by some combination of opening and closing tabs, but I haven't yet figured out what exactly that is.

How many tabs are open? I'm guessing that if it is more than a certain number (let's say 10) and your current tab is more than that number, Opera may be assigning the current tab as 1 ...

Thanks for the reply, and great guess.

Unforunately . . . I have two pinned tabs that are always there, plus generally one to five or six more. I know I haven't gone over 10 today, but have still experienced a few number switches. It was certainly worth a check though: I just opened a dozen tabs (some Google, some blank) and the numbering system remained what it had been immediately previously (the second option above). The tenth tab, incidentally, was labeled "10" (with "0" as the shortcut key) and subsequent tabs weren't given numbers (with shortcut keys selected from letters in the tab names).