Qt: Fixing the issue #1149

[butic-user]

Solves issue #1149: [Feature request] Closing the My Address window by left mouse clicking anywhere out of the My Address window

[furszy]

Hello, thanks for the first contribution. Feedback:

1. This isn't solving [Feature request] Closing the My Address window by left mouse clicking anywhere out of the My Address window #1149. The dialog is not closing when you press anywhere on the screen. A different window flag will not change this behavior, the opaque background functionality doesn't exist on the QT framework.
   
   To solve it, you will need to create a new signal on the base window class (subclassing the opaque background functionality and adding a click event) and connect every dialog that is launched with it, so when it's pressed, the dialog and the background gets closed.

2. Please read the CONTRIBUTING.md document, Squashing Commits section. You will find there some tips and step by step guides to squash down your changes into one single commit.

3. Please try to be descriptive on the PR title. Link another issue isn't the best (same as with (2), examples can be found in the CONTRIBUTING.md doc).

[random-zebra]

I tried this on linux.
It does close the window by clicking outside of it, but the dialog isn't open on top of the current window with opaque background (in fact, it actually shows up on a different monitor).

I also think that, if we want to bring the feature requested in #1149, it should be done for all modal dialogs in the application, not just this one.