If currently mining, automatically change number of threads when combobox changes

src/mainwindow.cpp

@@ -1566,6 +1566,29 @@ void MainWindow::setupMiningTab() {
         button1->setObjectName("startmining");
         button2->setObjectName("stopmining");
 
+        connect(combo, QOverload<int>::of(&QComboBox::currentIndexChanged), [=](int index){
+            auto button1 = ui->tabWidget->findChild<QPushButton *>("startmining");
+            if(button1 != nullptr) {
+                DEBUG("found start mining button and enabled=" << button1->isEnabled() );
+
+                if(button1->isEnabled()) {
+                    // if start mining button is enabled, we are not currently mining, so do nothing
+                    return;
+                }
+            }
+
+            // if we are currently mining and thread count combo changes, change our genproclimit
+            // to that number of threads, instead of users have to stop and restart mining, which
+            // is dumb and non-intuitive
+
+            DEBUG("combobox changed index=" << index);
+            int threads = index+1;
+            DEBUG("changing number of threads to " << threads);
+            rpc->setGenerate(threads, [=] (QJsonValue response){
+                DEBUG("setgenerate response=" << response);
+            });
+        });
+
         QObject::connect(button1, &QPushButton::clicked, [&] () {
             DEBUG("START MINING");
             int threads = 1;