Fixes

app/src/main/java/eu/faircode/email/FragmentDialogSearch.java

@@ -15,6 +15,7 @@ import android.view.View;
 import android.view.WindowManager;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputMethodManager;
+import android.widget.AdapterView;
 import android.widget.AutoCompleteTextView;
 import android.widget.Button;
 import android.widget.CheckBox;
@@ -196,6 +197,23 @@ public class FragmentDialogSearch extends FragmentDialogBase {
             }
         });
 
+        spMessageSize.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
+            @Override
+            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
+                parent.post(new Runnable() {
+                    @Override
+                    public void run() {
+                        parent.requestFocusFromTouch();
+                    }
+                });
+            }
+
+            @Override
+            public void onNothingSelected(AdapterView<?> parent) {
+                // Do nothing
+            }
+        });
+
         btnAfter.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {

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

@@ -371,7 +371,7 @@
             app:constraint_referenced_ids="
             cbSearchIndex,tvSearchIndexHint,cbSenders,cbRecipients,cbSubject,cbKeywords,cbMessage,tvSearchTextHint,
             tvAnd,cbUnseen,cbFlagged,cbHidden,cbEncrypted,cbAttachments,
-            tvMessageSize,spMessageSize,
+            tvMessageSize,spMessageSize,tvSizeHint,
             btnAfter,btnBefore,tvBefore,tvAfter" />
     </androidx.constraintlayout.widget.ConstraintLayout>
 </eu.faircode.email.ScrollViewEx>