Replace alert dialog with material alert dialog

app/src/main/java/com/hippo/ehviewer/ui/MainActivity.java

@@ -42,6 +42,7 @@ import androidx.annotation.StringRes;
 import androidx.appcompat.app.AlertDialog;
 import androidx.drawerlayout.widget.DrawerLayout;
 
+import com.google.android.material.dialog.MaterialAlertDialogBuilder;
 import com.google.android.material.navigation.NavigationView;
 import com.google.android.material.snackbar.Snackbar;
 import com.hippo.ehviewer.AppConfig;
@@ -320,6 +321,7 @@ public final class MainActivity extends StageActivity
         View headerLayout = mNavView.getHeaderView(0);
         mAvatar = (LoadImageView) ViewUtils.$$(headerLayout, R.id.avatar);
         mDisplayName = (TextView) ViewUtils.$$(headerLayout, R.id.display_name);
+        mDrawerLayout.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);
 
         updateProfile();
 
@@ -347,7 +349,7 @@ public final class MainActivity extends StageActivity
         if (null == uniFile || uniFile.ensureDir()) {
             return;
         }
-        new AlertDialog.Builder(this)
+        new MaterialAlertDialogBuilder(this)
                 .setTitle(R.string.waring)
                 .setMessage(R.string.invalid_download_location)
                 .setPositiveButton(R.string.get_it, null)