Getting rid of BufferView * current_view from InsetGraphics

[Angus Leeming]

InsetGraphics currently contains the following code:

extern BufferView * current_view;
void InsetGraphics::statusChanged()
{
        current_view->updateInset(this, false);
}

InsetGraphics::statusChanged() is connected to the signal 
grfx::Loader::statusChanged, emitted when the graphics file is loaded into 
memory (f.ex).

Now InsetGraphics::draw(BufferView * bv, ...) does the drawing of the inset. 
My idea is to define a signal to add to InsetGraphics (or rather to the 
private std::auto_ptr<Cache> const cache_):
        boost::signal2<void, Inset * inset, bool); updateInset;

and to connect it in InsetGraphics::draw:
        cache_->updateInset.connect(
                boost::bind(&BufferView::updateInset, bv, _1, _2));

We can then get rid of current_view from InsetGraphics and have
void InsetGraphics::statusChanged()
{
        cache_->updateInset(this, false);
}

which will call all the appropriate BufferViews.

So, questions:
1. BufferView would now derive from boost::trackable. Ok?
2. Is there some function that will tell me whether a signal is already 
connected to a particular slot? (So that I don't conect to the same 
BufferView * bv multiple times in InsetGraphics::draw).
3. Is the approach "reasonable"?

Angus