Re: Invoking GTK main thread from other threads

That said, it's equally possible I am wrong and SignalIdle technically is
not thread-safe. I can't really make sense of the wording in the docs...

for connect_once(), we have:

> Because sigc::trackable
<http://library.gnome.org/devel/libsigc++/unstable/structsigc_1_1trackable.html>
is not thread-safe, if the slot represents a non-static method of a class
deriving from sigc::trackable
<http://library.gnome.org/devel/libsigc++/unstable/structsigc_1_1trackable.html>,
and the slot is created by sigc::mem_fun()
<http://library.gnome.org/devel/libsigc++/unstable/group__mem__fun.html#gadf6b6d22c503b439019f0a2e77352419>,
connect_once()
<https://developer.gnome.org/glibmm/stable/classGlib_1_1SignalIdle.html#a94217dc63e35f96b5cee4c48f2cdd020>
should only be called from the thread where the SignalIdle
<https://developer.gnome.org/glibmm/stable/classGlib_1_1SignalIdle.html>
object's MainContext
<https://developer.gnome.org/glibmm/stable/classGlib_1_1MainContext.html>
runs. You can use, say, boost::bind() or, in C++11, std::bind()
<http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01513.html#ga7b2eddb726568256e49824ad01a05099>
or a C++11 lambda expression instead of sigc::mem_fun()
<http://library.gnome.org/devel/libsigc++/unstable/group__mem__fun.html#gadf6b6d22c503b439019f0a2e77352419>
.

That makes enough sense and still leaves plenty cases for which it'll
definitely be safe.

but for connect(), we have the unconditional:

> This method is not thread-safe. You should call it, or manipulate the
returned sigc::connection
<http://library.gnome.org/devel/libsigc++/unstable/structsigc_1_1connection.html>
object, only from the thread where the SignalIdle
<https://developer.gnome.org/glibmm/stable/classGlib_1_1SignalIdle.html>
object's MainContext
<https://developer.gnome.org/glibmm/stable/classGlib_1_1MainContext.html>
runs.

I would expect the same condition(s) to apply to connect() as to
connect_once() - since AFAIK, all the once version does is just disconnect
itself automatically - but I might just be missing some obvious reason why
this can't be the case. And now I feel like maybe I've had this discussion
in the past...!

Anyway, I mentioned it because I have had the usual crashy behaviour
symbolic of trying to access widgets in threads other than the main one, in
my own projects, and wrapping the code doing said accesses in a lambda run
in SignalIdle has always fixed it. Maybe I've just been lucky so far?

Thoughts/corrections to me from those more experienced at doing
multi-threading with gtkmm are welcome.

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