Small improvement

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

@@ -96,8 +96,10 @@ public class ActivityWidget extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
-                btnColor.setColor(Color.TRANSPARENT);
+                if (isChecked) {
-                setBackground();
+                    btnColor.setColor(Color.TRANSPARENT);
+                    setBackground();
+                }
             }
         });
 

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

@@ -69,7 +69,8 @@ public class ActivityWidgetSync extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
-                btnColor.setColor(Color.TRANSPARENT);
+                if (isChecked)
+                    btnColor.setColor(Color.TRANSPARENT);
             }
         });
 

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

@@ -103,7 +103,8 @@ public class ActivityWidgetUnified extends ActivityBase {
         cbSemiTransparent.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
             @Override
             public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
-                btnColor.setColor(Color.TRANSPARENT);
+                if (isChecked)
+                    btnColor.setColor(Color.TRANSPARENT);
             }
         });