When the topic minor mode is turned on, a new T submap will be available. In addition, a few of the standard keys change their definitions slightly.
In general, the following kinds of operations are possible on topics. First of all, you want to create topics. Secondly, you want to put groups in topics and to move them around until you have an order you like. The third kind of operation is to show/hide parts of the whole shebang. You might want to hide a topic including its subtopics and groups, to get a better overview of the other groups.
Here is a list of the basic keys that you might need to set up topics the way you like.
Prompt for a new topic name and create it
(gnus-topic-create-topic).
“Indent” the current topic so that it becomes a sub-topic of the
previous topic (gnus-topic-indent). If given a prefix,
“un-indent” the topic instead.
“Un-indent” the current topic so that it becomes a sub-topic of the
parent of its current parent (gnus-topic-unindent).
The following two keys can be used to move groups and topics around. They work like the well-known cut and paste. C-k is like cut and C-y is like paste. Of course, this being Emacs, we use the terms kill and yank rather than cut and paste.
Kill a group or topic (gnus-topic-kill-group). All groups in the
topic will be removed along with the topic.
Yank the previously killed group or topic
(gnus-topic-yank-group). Note that all topics will be yanked
before all groups.
So, to move a topic to the beginning of the list of topics, just hit C-k on it. This is like the “cut” part of cut and paste. Then, move the cursor to the beginning of the buffer (just below the “Gnus” topic) and hit C-y. This is like the “paste” part of cut and paste. Like I said—E-Z.
You can use C-k and C-y on groups as well as on topics. So you can move topics around as well as groups.
After setting up the topics the way you like them, you might wish to hide a topic, or to show it again. That’s why we have the following key.
Either select a group or fold a topic (gnus-topic-select-group).
When you perform this command on a group, you’ll enter the group, as
usual. When done on a topic line, the topic will be folded (if it was
visible) or unfolded (if it was folded already). So it’s basically a
toggling command on topics. In addition, if you give a numerical
prefix, group on that level (and lower) will be displayed.
Now for a list of other commands, in no particular order.
Move the current group to some other topic
(gnus-topic-move-group). This command uses the process/prefix
convention (see Process/Prefix).
Go to a topic (gnus-topic-jump-to-topic).
Copy the current group to some other topic
(gnus-topic-copy-group). This command uses the process/prefix
convention (see Process/Prefix).
Hide the current topic (gnus-topic-hide-topic). If given
a prefix, hide the topic permanently.
Show the current topic (gnus-topic-show-topic). If given
a prefix, show the topic permanently.
Remove a group from the current topic (gnus-topic-remove-group).
This command is mainly useful if you have the same group in several
topics and wish to remove it from one of the topics. You may also
remove a group from all topics, but in that case, Gnus will add it to
the root topic the next time you start Gnus. In fact, all new groups
(which, naturally, don’t belong to any topic) will show up in the root
topic.
This command uses the process/prefix convention (see Process/Prefix).
Move all groups that match some regular expression to a topic
(gnus-topic-move-matching).
Copy all groups that match some regular expression to a topic
(gnus-topic-copy-matching).
Toggle hiding empty topics
(gnus-topic-toggle-display-empty-topics).
Toggle the process mark for all groups in the current topic
(gnus-topic-mark-topic). This command works recursively on
sub-topics unless given a prefix.
If gnus-process-mark-toggle is nil, set the process mark
for the current topic.
Remove the process mark from all groups in the current topic
(gnus-topic-unmark-topic). This command works recursively on
sub-topics unless given a prefix.
Run all expirable articles in the current group or topic through the
expiry process (if any)
(gnus-topic-expire-articles). (see Expiring Mail).
Rename a topic (gnus-topic-rename).
Delete an empty topic (gnus-topic-delete).
List all groups that Gnus knows about in a topics-ified way
(gnus-topic-list-active).
Go to the next topic (gnus-topic-goto-next-topic).
Go to the previous topic (gnus-topic-goto-previous-topic).
Edit the topic parameters (gnus-topic-edit-parameters).
See Topic Parameters.