Show data size label only when a format is selected

Fixes #1352

Signed-off-by: Lukas Holecek <hluk@email.cz>

src/gui/clipboarddialog.cpp

@@ -168,8 +168,13 @@ void ClipboardDialog::onListWidgetFormatsCurrentItemChanged(
         addText();
     }
 
-    ui->labelProperties->setText(
-                tr("<strong>Size:</strong> %1 bytes", "Size of data in bytes").arg(bytes.size()) );
+    if (current) {
+        ui->labelProperties->setText(
+                tr("<strong>Size:</strong> %1 bytes", "Size of clipboard/item data in bytes")
+                .arg(bytes.size()) );
+    } else {
+        ui->labelProperties->setText(QString());
+    }
 }
 
 void ClipboardDialog::onActionRemoveFormatTriggered()