text window starts scrolling at bottom (#20587)

* text starts scrolling at bottom

* comment
old-commit-hash: 9e4748db8b

selfdrive/ui/qt/text.cc

@@ -1,5 +1,6 @@
 #include <QLabel>
 #include <QWidget>
+#include <QScrollBar>
 #include <QPushButton>
 #include <QVBoxLayout>
 #include <QApplication>
@@ -23,6 +24,11 @@ int main(int argc, char *argv[]) {
   scroll->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
   layout->addWidget(scroll, 0, 0, Qt::AlignTop);
 
+  // Scroll to the bottom
+  QObject::connect(scroll->verticalScrollBar(), &QAbstractSlider::rangeChanged, [=](){
+    scroll->verticalScrollBar()->setValue(scroll->verticalScrollBar()->maximum());
+  });
+
   QPushButton *btn = new QPushButton();
 #ifdef __aarch64__
   btn->setText("Reboot");