[Qt-interest] Events and objects...

[BRM]

I'm revisiting a problem I partially solved a while ago per layouts and snapping 
widgets in and out. The old solution derived from QGridLayout and required a 
customized widget to interact with it; however, it is problematic in that it 
does not always clear out the columns. I had thought of a couple other 
approaches, one of which I am now attempting, but I find there may be a 
problem...

Original Approach
- Derive a new object that checks the mouse double click event. The new object 
basically just says if it has a parent, then pop it out; otherwise, pop it back 
in.
- Derive a new sub layout from QGridLayout that receives a signal on the pop 
in/out events to do so; adding/removing it as appropriate, and keeping track of 
removed widgets.
- If a widget is removed, then free up the grid above it so things can slid up 
(primarily done only when everything is remove from the display).

New Approach 1
- Instead of using QGridLayout, derive from QLayout.
- Use a master QHBoxLayout to manage the columns with each column having its own 
QVBoxLayout
- Add/remove items to each column as desired via insertWidget() to get it in the 
right spot.
- Logic for the pop in/pop out is still in the layout

New Approach 2
- Like New Approach 1 but use the approach of QMdiArea
- Instead of using a specialized QWidget to like in the Original Approach, use a 
custom QWidget (aka QSubWidget) that manages a single normal QWidget.
- Manage the pop in/out from the QSubWidget

I'd really like to do New Approach 2 as it makes the whole thing a little more 
generic - and my other widgets don't need to be specifically derived from the 
custom widget, as done in my original approach.
However, to do so the QSubWidget needs to have access to the mouse double-click 
event from the normal QWidget - which at least in Qt 4.5 is a protected virtual 
function.
My question is - without requiring something to be specifically derived from a 
specific class, is there a way to access the mouse double-click events of 
another widget?

I basically need to just know when a double click happens - even if there was an 
associated signal with the double click it would suffice.

Or is there a better approach?

TIA,

Ben