I made some changes that will allow the change in time not to affect the tickets as well as the visualization of the "worked" tickets.

Plus I also added some functionality like:

• display 30, 60, 120, 365 days (30 default)
• the legend is outside the grab
• ability to stack the graph
• clicking on a label on the legend will hide that part of the graph
• fixed the open tickets to be based on the end of the day for that day and not on the next day

My pull is here:
https://github.com/EffEPi/TracTicketGraph

The ticketgraph will show the last 90 days by default which is perfectly fine. But you are able to enter bigger numbers like 10000. In my test I could not go further than 738632 on https://core.trac.wordpress.org/ticketgraph?days=738632. Amazing to see the bunch of closed tickets around the year 200! I'd expect the graph to simply show all he has instead of going back in time, if you enter numbers like these.

Regarding Ticket: https://core.trac.wordpress.org/ticket/58388

They told me to come here.

Looks like this can easily be patched around
\ticketgraph\ticketgraph.py, L. 98

days_back = req.args.getint('days', self.default_daysback)

by something like

max_days_back = 3000  # Maximum number of days allowed

days_back = req.args.getint('days', self.default_daysback)

if days_back > max_days_back:
    days_back = max_days_back

Query by ticket type, as in nacin@cf3ce11.

The value is currently fixed at 90. We could make it configurable.

the legend in the top right corner obscures the most "interesting" (ie the most recent) data. maybe move to the left corner or outside the graph.

Since the graph is labeled "Ticket Graph", I think it's highly redundant to have the four labels in the legend be "Closed tickets", "New tickets", "Reopened tickets" and "Open tickets". Striking 'ticket' from each of these makes it more concise, and obscures less of the graph data.

Seeing this error with Trac 1.2.1:

jquery.flot.min.js:1 Uncaught TypeError: Cannot read property 'msie' of undefined
    at c (jquery.flot.min.js:1)
    at new B (jquery.flot.min.js:1)
    at Function.C.plot (jquery.flot.min.js:1)
    at HTMLDocument.<anonymous> (ticketgraph.js:10)
    at j (jquery.js:2)
    at Object.fireWith [as resolveWith] (jquery.js:2)
    at Function.ready (jquery.js:2)
    at HTMLDocument.J (jquery.js:2)