When a overloaded method is typed in an tooltip is shown for the parameters of the method.
When there are many overloads (e.g. QString::arg() method) there are 20 overloads :-O

When popping up the first (by what indexing metric ?) overload is shown.

Pressing the cursor down shows the other overloads.
Finally (overload 12 of 20) I arrived at my desired overload for double values.
But when pressing a comma the first overload is shown again.... that is not the one for double that I wanted to use.
So pressing 12 cursor down again... until the next ','

Attached are screenshots just before pressing ',' and after pressing ','