qt, refactor: Keep CoinControlDialog in the main event loop

src/qt/sendcoinsdialog.cpp

@@ -914,9 +914,9 @@ void SendCoinsDialog::coinControlFeatureChanged(bool checked)
 // Coin Control: button inputs -> show actual coin control dialog
 void SendCoinsDialog::coinControlButtonClicked()
 {
-    CoinControlDialog dlg(*m_coin_control, model, platformStyle);
-    dlg.exec();
-    coinControlUpdateLabels();
+    auto dlg = new CoinControlDialog(*m_coin_control, model, platformStyle);
+    connect(dlg, &QDialog::finished, this, &SendCoinsDialog::coinControlUpdateLabels);
+    GUIUtil::ShowModalDialogAndDeleteOnClose(dlg);
 }
 
 // Coin Control: checkbox custom change address