Give up

app/src/main/java/com/keylesspalace/tusky/ComposeActivity.java

@@ -647,6 +647,10 @@ public class ComposeActivity extends BaseActivity implements ComposeOptionsFragm
         }
     }
 
+    /**
+     * A∖B={x∈A|x∉B}
+     * @return all elements of set A that are not in set B.
+     */
     private static List<String> setDifference(List<String> a, List<String> b) {
         List<String> c = new ArrayList<>();
         for (String s : a) {

app/src/main/res/layout/activity_compose.xml

@@ -63,7 +63,6 @@
                 android:hint="@string/hint_compose"
                 android:inputType="text|textMultiLine|textCapSentences"
                 android:dropDownWidth="wrap_content"
-                android:dropDownHeight="58dp"
                 android:completionThreshold="2" />
 
             <HorizontalScrollView