Find Usages for a signal will not report any usages in a connect() call, unless the connect() call happens to be in a method of the class which declares the signal.

Let's say I have a class Foo which declares a signal foo(). Finding usages of foo() will return the following lines:

1. The declaration of foo(),
2. All `emit foo();` lines
3. All `connect(this, SIGNAL(foo()), something, SLOT(bar())` lines which occur in a method of Foo

But it will not return the following lines:

1. All `connect(someFooObj, SIGNAL(foo()), something, SLOT(bar())` lines which occur in a free function or a method of a class other than Foo.