Thunderbird Calendar Cleanup

The thought to create a copy of my Thunderbird profile did not cross my mind until the last power failure. After each power failure I found that I have to setup my mail account, and that all my events were “lost”.
Wellm the events were not exactly lost, but a new calendar id was created, which is to be used to find all the events and their relevant properties in the calendar extension’s database. The database itself is an SQLite file, and in my system is located under ‘~/.thunderbird/default-dir/calendar-data/local.sqlite’
(Change the default-dir name to your local name, it is by default the one that ends with ‘.default*.

Finding the Current Calendar Id

The calendar id is the value of the Thunderbird’s user preference ‘calendar.list.sortOrder’. You can view this variables by choosing from the menu:
preferences->preferences->preferences*, and then from the window opend, choosing the Advanced tab, and then clicking the “Config Editor* button.
Continue at your own risk…
Now, if you haven’t imported your calendar using Events And Tasks->Export.
You can connect to the database using:

sqlite3 /path/to/local.sqlite

From now on, I’ll assume you only have one calendar.

SQLite Tables

The tables, indexes, trigges and other database entities are stored in a table named ‘sqlite_master’. To find tables, run the query

select name from sqlite_master
where type='table';

For each table column, run the query:

pragma table_info(table_name);

The result will be:


Replace table_name by a table name, for example:

pragma table_info(cal_events)

The result will be:


Finding the Last Calendar Id

Now, I guess that an event in the last calendar has the latest event start date.
A good query to find that event can be:

select cal_id, title, event_start
from cal_events
order by event_start;

Let us call the most recent value calendar id “old-cal-id”, and the new calendar id “new-cal-id*

Updating and Deleting

I suggest that you perform update and delete queries within transaction, so if something goes wrong you can rollback.
Begin a transaction by running the command:

begin transaction

Now, for each table that has the column cal_id, run the query:

update table_name
set cal_id="new-cal-id"
where cal_id="old-cal-id"

Replace table_name by a name of a table that has the column cal_id, for example:

update cal_event
set cal_id="new-cal-id"
where cal_id="old-cal-id";

Now, to delete the rest, run:

delete from table_name
where cal_id != "old-cal-id";

If everything’s fine, it’s time to commit your transaction by running:


To learn more about SQLite, visit


Main Window Operation In Matplotlib

Matplotlib is a MATLAB-like library that allows Python programmers to create images and animations. For example, you can easily draw a graphic representation of functions with Y (and maybe Z) values generated by numpy and scipy functions.
Matplotlib can also be interactive and handle events. The command mpl_connect is used for connecting an event with a callback function.

The Backend Layer

Someone on the IRC has challenged me with questions on how to perform some operations when the window is closed. In addition, I want the window title to be other than the default, “Figure 1”.
enter image description here

Well, the layer that handles the main window is the backend layer,
To find what backend Matplotlib uses, you can add the line
print type(fig.canvas)
The result may be something like:
<class 'matplotlib.backends.backend_gtkagg.FigureCanvasGTKAgg'>
This means that the backend used is ‘GtkAgg’.
With the function ‘dir’, I’ve found that the canvass has a function named get_toplevel, and the returned value of fig.canvass.get_toplevel() is an object of type gtk.Window.
This object has the methods of a GTK window. So you can change its title with the ‘set_titlemethod. For example:
fig.canvas.get_toplevel().set_title(‘Rubic Cube’)
You can tell your application what to do when the user closes the window, by calling its 'connect' method, with 'destroy' for first arguments.
For example:
fig.canvas.get_toplevel().connect(‘destroy’, destroyFunc, ‘Goodbye, cruel world!’)
destroyFunc` is a function that accept 2 arguments (3 if a class member): the widget where the event has occurred and additional user defined data.
More about Python FTK can be found at

Last but not least, you can specify the backend Matplotlib will use, by calling the ‘use’ method of matplotlib.
For example:

Note: This method should be called before importing ‘pyplot’.

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