Done That!
Early in my flying of the (slider) 9A, I "thought" I had locked the canopy - yes, I followed the checklist...
But alas at about 50 feet I hear a thump and started looking for what may have caused it. With ANR headset, the noise from the extra wind was cancelled. So at 1200' I finally discovered the canopy was in fact not latched. At 120 Kts, there's nothing you can do to budge that sucker! Slowing to 75 Kts and preparing to land at 7S3 (Twin Oaks) I let the traffic know I had a bit of a "problem" just in case slower airspeed may cause some unexpected surprises.
Landing went smoothly and after clearing the runway I securely latched the canopy and went about my business for the rest of the flight regimen.
The 6, 7, & 9 sliders are designed with a downward "swoop" at the aft. This causes some downward airflow pressure that literally pushes the canopy forward (unless that sucker is way open - which you would surely realize before take off ???)
End result is that I added three more references to CLOSED AND LOCKED in the checklist and if anyone is in the plane with me, I ask them to put their hand on the handle (as a reminder) until I get the the departure runway. They have all understood when I explain that I don't want to be distracted and forget...
Id I'm by myself, then I hang my hand on the latch...