Holding Shift or S to select several sprites only seems to properly select them all when one starts on the top left sprite they are selecting.
While actions such as copying, flipping, and moving work properly when selecting from the top left, it appears that when starting at a different corner it instead treats the selection as if only the initial tile was selected instead. This creates particularly odd effects when at levels of zoom besides 1x:
Noticed some presumably unintended odd behavior in the sprite editor:
It seems that any time the selected region is flipped while not over its initial position, pixels are changed underneath it. Using version 0.2.1b on a Mac.
Edit: I will note that something like this seems like it could actually be somewhat useful behavior, as it lets one duplicate an already selected area within a sprite without having to copy and deselect it, but it's pretty odd right now. For example:
Noticed another oddity with moving selected regions while testing this: if one has copied a group of pixels, then selecting a region, pasting with CTRL-V, and moving the selected region will cause the pasted pixels to disappear.
The map editor also appears to be having some similar issues: