If you can identify the manufacturer of the door, contact them. Otherwise, I'd caulk the holes and look for some paint at an art supply store that closely matches the door trim.

You could plug the holes with with an epoxy putty but you'll still have to do the paint as Randy suggested. I'm assuming the tenants took the security bar with them. Why not put in a replacement security bar that uses the existing holes? A sliding door is very easy to slide open, even when locked, without a security bar.

Even a security bar does not provide much protection if there are not some screws in the upper track to prevent the door from being lifted up and removed from the lower track.

Otoh, if they want in bad enough, they'll simply break the glass! Same goes for windows. That doesn't mean you shouldn't take security measures, but unfortunately, if the bad guys want in bad enough, it's going to happen. In so.cal, a homeowner went to extreme and costly measures to wrought iron over the windows, installed security doors, and wrought iron fencing. The bad guys climbed up on the roof and entered theough a sky light!

"Otoh, if they want in bad enough, they'll simply break the glass!

Leaving a slider so it can simply be lifted off the tracks is about the same as leaving it wide open.

No tools, nothing to break the glass, just lift up the door.

Breaking the safety glass required for many years in a slider also makes a LOT of noise unless they know how to break safety glass quietly (there is a way).

"Leaving a slider so it can simply be lifted off the tracks is about the same as leaving it wide open".

Probably the easiest,(and quietest), way for the bad guys to get in. They say that the bad guys are typically looking for the easiest route, that would be one of them. No real full proof way to make a place 100% safe, but the harder the points of entry, the greater the chance they'll seek an easier avenue at another residence. I like the screws in the upper track idea, simple fix!

I've always heard that sliders could be lifted off the track which is why we never bothered with the security bar (plus they look kind of tacky, at least on this door, which is made to look like a paneled french door). Would the screws be enough to fix the problem or would it be more secure to install actual french doors? We have those on the front of the house, but they seem pretty flimsy too as there is no center bar, just the two doors meeting each other in the middle. We mostly just rely on living in a safe neighborhood, which ain't the best plan!

Thanks for all the input! We will try the patch and paint and hope it will blend.

"Would the screws be enough to fix the problem or would it be more secure to install actual french doors?"

You can secure a slider against lifting by putting in 2-3 screws in the upper track and leaving them sitting high.

You need to make sure they are high enough to clear the door when it operates.

Even drywall screws are adequate, but you will probably need to drill a pilot hole through the aluminum track for them (if you have drywall screws for metal studs they usually go in without a pilot hole).

I usually run them in almost all the way, check the door, then start backing them out a little at a time until they hit the door, then drive them back in about 1/8 inch.

Thanks, brickeye. Those are good, clear directions. I think even I can follow those! LOL

(thanks for your help on the Corian sink issue, too)