use rounded corners at the Delete etc backgrounds

app/src/main/kotlin/com/simplemobiletools/keyboard/views/MyKeyboardView.kt

@@ -335,7 +335,7 @@ class MyKeyboardView @JvmOverloads constructor(context: Context, attrs: Attribut
                         MSG_SHOW_PREVIEW -> showKey(msg.arg1)
                         MSG_REMOVE_PREVIEW -> mPreviewText!!.visibility = INVISIBLE
                         MSG_REPEAT -> if (repeatKey()) {
-                            val repeat: Message = Message.obtain(this, MSG_REPEAT)
+                            val repeat = Message.obtain(this, MSG_REPEAT)
                             sendMessageDelayed(repeat, REPEAT_INTERVAL.toLong())
                         }
                         MSG_LONGPRESS -> openPopupIfRequired(msg.obj as MotionEvent)

app/src/main/res/drawable/key_pressed_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
+    <item>
+        <shape android:shape="rectangle">
+            <solid android:color="@color/key_press_color" />
+            <corners android:radius="@dimen/medium_margin" />
+        </shape>
+    </item>
+</layer-list>

app/src/main/res/drawable/keyboard_key_selector.xml

@@ -4,5 +4,5 @@
     <item android:drawable="@drawable/minikeyboard_selected_background" android:state_focused="true" />
 
     <!-- used at clicking some keys on the main keyboard -->
-    <item android:drawable="@color/key_press_color" android:state_pressed="true" />
+    <item android:drawable="@drawable/key_pressed_background" android:state_pressed="true" />
 </selector>