gui: Prevent processing duplicate payment requests

[promag]

Considering the following from Qt src/plugins/platforms/cocoa/qcocoaapplicationdelegate.mm#L267

- (void)application:(NSApplication *)sender openFiles:(NSArray *)filenames
{
    Q_UNUSED(filenames);
    Q_UNUSED(sender);

    for (NSString *fileName in filenames) {
        QString qtFileName = QString::fromNSString(fileName);
        if (inLaunch) {
            // We need to be careful because Cocoa will be nice enough to take
            // command line arguments and send them to us as events. Given the history
            // of Qt Applications, this will result in behavior people don't want, as
            // they might be doing the opening themselves with the command line parsing.
            if (qApp->arguments().contains(qtFileName))
                continue;
        }
        QWindowSystemInterface::handleFileOpenEvent(qtFileName);
    }

And that a2714a5 was merged, now Qt isn't able to filter out the above notifications, and then a QFileOpenEvent event is delivered to PaymentServer::eventFilter, which in turn (re)adds the payment request.

This change fixes #17025, but makes sense regardless of the issue.

[laanwj]

Concept ACK, but is there is no specific way to recognize and ignore these Mac-only events?

Changing the code for all platforms here last-minute seems a bit risky.

If you do this, this needs a comment at the handling site that payment requests can be duplicated due to platform-specific "features" and that's why it is like this.

Edit: What about ignoring the command line passed URIs on MacOSX, because we know we'll get notification for them anyway?

[laanwj]

Though I guess this fixes #2302 as well?

[promag]

Edit: What about ignoring the command line passed URIs on MacOSX, because we know we'll get notification for them anyway?

Other options:

• during init, compare QFileOpenEvent path with the ones from argv and ignore if duplicate
• pass non-options to QApplication so that Qt behavior remains the same.

But this change also prevents processing duplicate payments from the command line, like

bitcoin-qt -regtest "bitcoin:bcrt1qu7nl0nxfqwhrrf6v0t60asvq3dympgqdhg03rn?amount=0.00010000" "bitcoin:bcrt1qu7nl0nxfqwhrrf6v0t60asvq3dympgqdhg03rn?amount=0.00010000"

[laanwj]

Nah, this seems fine, utACK 3f89e1e

[Sjors]

ACK 3f89e1e on macOS 10.14.6

[achow101]

Code review ACK 3f89e1e