Small improvement

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

@@ -96,9 +96,11 @@ public class ActivityWidget extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                if (isChecked) {
                     btnColor.setColor(Color.TRANSPARENT);
                     setBackground();
                 }
+            }
         });
 
         btnColor.setOnClickListener(new View.OnClickListener() {

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

@@ -69,6 +69,7 @@ public class ActivityWidgetSync extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                if (isChecked)
                     btnColor.setColor(Color.TRANSPARENT);
             }
         });

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

@@ -103,6 +103,7 @@ public class ActivityWidgetUnified extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                if (isChecked)
                     btnColor.setColor(Color.TRANSPARENT);
             }
         });