notes: add icons to use previous/next event as template

app/src/main/java/it/danieleverducci/lunatracker/MainActivity.kt

@@ -312,7 +312,6 @@ class MainActivity : AppCompatActivity() {
             }
 
             if (nextEvent != null) {
-                nextTextView.visibility = View.VISIBLE
                 nextTextView.setOnClickListener {
                     notesET.setText(nextEvent.notes)
                     if (useQuantity) {
@@ -320,12 +319,13 @@ class MainActivity : AppCompatActivity() {
                     }
                     updateContent(nextEvent)
                 }
+                nextTextView.alpha = 1.0f
             } else {
-                nextTextView.visibility = View.GONE
+                nextTextView.setOnClickListener {}
+                nextTextView.alpha = 0.5f
             }
 
             if (prevEvent != null) {
-                prevTextView.visibility = View.VISIBLE
                 prevTextView.setOnClickListener {
                     notesET.setText(prevEvent.notes)
                     if (useQuantity) {
@@ -333,8 +333,10 @@ class MainActivity : AppCompatActivity() {
                     }
                     updateContent(prevEvent)
                 }
+                prevTextView.alpha = 1.0f
             } else {
-                prevTextView.visibility = View.GONE
+                prevTextView.setOnClickListener {}
+                prevTextView.alpha = 0.5f
             }
         }