Can't close a QWidget from itself

[tonnot]

I have a floating widget named float_panel; I create it from another Widget currently showed.

I show it so:

my_float_panel = new Ui_float_panel(this);

my_float_panel = new Ui_float_panel(this);

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Ok, this float_panel has a button to close the Qwidget float_panel instance itself.
Inside the click_event of this button can I simply do: this->close() ?
(Now, I see (because I have a q_debug msg) I am inside the click_event, where I execute this->close(), but my widget remains visible .... )

Also I have tried to connect

connect(my_float_panel,SIGNAL(destroyed()),this, SLOT(float_panel_has_closed()));

connect(my_float_panel,SIGNAL(destroyed()),this, SLOT(float_panel_has_closed()));

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But without success.

Any idea what I'm doing bad ? Thanks.