This bug affects Minecraft 1.6.1 and Minecraft 1.6.2 (not the previous versions).
Try to snap the Minecraft window on the right/left border of the screen on Windows 7/8 so that the Minecraft window takes half of the screen (this is a specific feature of Windows 7 and 8).
Now, go to another program and when yo go back to Minecraft, the window is no longer snapped and resumes its original positin and size.
Linked issues
Comments 3
Duplicate of MC-8124, please use the search function to see if your bug has already been submitted. Currently over 58% of tickets are being resolved as duplicate.
Or duplicate of MC-14323
It can be troublesome, I often need to open another program in parallel with Minecraft and the Snap feature of Windows is very usefull for that.
Sorry if my English is bad, it's not my native language.