Fix AlertDialogFragment

mobile/src/main/java/be/mygod/vpnhotspot/AlertDialogFragment.kt

@@ -7,10 +7,17 @@ import android.os.Bundle
 import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.DialogFragment
 
+/**
+ * Based on: https://android.googlesource.com/platform/packages/apps/ExactCalculator/+/8c43f06/src/com/android/calculator2/AlertDialogFragment.java
+ */
 abstract class AlertDialogFragment : DialogFragment(), DialogInterface.OnClickListener {
     protected abstract fun AlertDialog.Builder.prepare(listener: DialogInterface.OnClickListener)
     open val data: Intent? get() = null
 
+    init {
+        setStyle(STYLE_NO_TITLE, 0)
+    }
+
     override fun onCreateDialog(savedInstanceState: Bundle?): AlertDialog =
             AlertDialog.Builder(requireContext()).also { it.prepare(this) }.create()