keyboard tray for reclined use without sliding

7.28: proj.gear/table for kybd in bed/the fencing star
make a fence to preventing kybd sliding:
. when using the table for kybd in bed
 I like to have the table at a slight angle,
 but then the kybd tends to slide off,
 so the table needs a little fence in front,
 and found just the adapter among my junk hardware:
 there are angle brackets for reinforcing cabinets .
 . I screwed a pair of them into place near the edge .
the keyboard tray