Few fixes to resolve all script warnings.

src/frameless

@@ -61,6 +61,7 @@ function selectScreen() {
 
     while [ -z "$selected" ]; do
       # Display the list of screens using Zenity
+      # shellcheck disable=SC2086
       selected=$(zenity --list --title "Select a Screen" --column "Index" --column "Screen Name" $screens)
       # Check the exit status of Zenity
       if [ $? -eq 1 ]; then
@@ -239,16 +240,16 @@ function showVideo() {
       y=30
       ;;
     "topright")
-      x=$(expr $width - 320 - 30)
+      x=$((width - 320 - 30))
       y=30
       ;;
     "bottomleft")
       x=30
-      y=$(expr $height - 240 - 30)
+      y=$((height - 240 - 30))
       ;;
     "bottomright")
-      x=$(expr $width - 320 - 30)
-      y=$(expr $height - 240 - 30)
+      x=$((width - 320 - 30))
+      y=$((height - 240 - 30))
       ;;
     *)
       echo "Invalid position specified"