Okay, I've been working on making tiles for my game and I've come across a few problems. Here are the example .caps (tileglitches.rar):
I'm making my sprites and backgrounds with pixel art and scaling it up for a chunky, retro look. I've made all my background tiles with Tiled Background (go figure) but when they scale up they have some graphical glitches. It seems that they're x, y offset is going haywire, so the Background Tile is jumping one pixel to the right or up when scrolling.
Take a look at the "640 zoom glitch.cap." Right off the bat you should see a little sliver of pixels to the left of the pipe. This sliver is actually the right-hand edge of the pipe being wrapped around to the left edge when it shouldn't be. Now take a look at the row of square tiles underneath the player. Run back and forth from there to the corner and you will see the row of tiles shifting up and down by one pixel.
Now take a look at the "fullscreen glitch.cap." This is in 320x240 fullscreen mode with no screen zoom. From where you start, jump up and down using Z. The tops of the pipe ends glitch out by 1 pixel vertically when the screen scrolls. This happens in windowed mode too, but it's not as easy to see. It's not as glitchy as 640x480 zoomed in, but a lot of people's monitors don't support 320x240 mode.
If you switch to 640x480 fullscreen resolution and set the screen zoom to 200x200 you get a similar effect to the windowed "640 zoom glitch.cap."
But wait, there's more... If you have a sprite set to "Center view on me" as I do with the purple player sprite, then zoom the view at runtime, it only scrolls to the object properly if "Unbounded scrolling" is checked for the layout. Open the "640 zoom glitch.cap" and uncheck "Unbounded scrolling" to see what I mean.
And last but not least, I've found that copy/pasting several objects in a row (sprites or tiled backgrounds) will eventually corrupt the IDE UI (it starts by making all the icons in the layers tab go haywire) and crash Construct. I don't know if there is a specific number of times you can copy/paste something before this happens, but I'll do some more testing and let you know. I had to save, quit, and reload Construct about three or four times at the first sign of UI corruption while placing all those tiles to keep it from crashing.
Whew... that's it. Sorry for the long post and dumping all this at once.
Edit: Submitted to bug tracker.