Require int for block height

src/mainwindow.cpp

@@ -911,12 +911,13 @@ void MainWindow::getBlock() {
 
     // First thing is ask the user for a block height
     bool ok;
-    auto blockheight = QInputDialog::getText(this, tr("Enter Block Height"),
-        QString(" ").repeated(140), // Pad the label so the dialog box is wide enough
-        QLineEdit::Normal, "", &ok);
+    int i = QInputDialog::getInt(this, tr("Get Block Info"),
+                                 tr("Enter Block Height:"), 1, 1, 2147483647, 1, &ok);
     if (!ok)
         return;
 
+    auto blockheight = QString::number(i);
+
     getRPC()->getBlock(blockheight, [=] (QJsonValue props) {
         QDialog d(this);
         Ui_GetBlock gb;