I have been using EGit to upload my stuff to github for a few months now.
But off late I do not see what files have been changed, and I dont know why. Please help.<
This looks like a problem with Mac OS X 10.10 and SWT, see Eclipse bug 446534 for details.
Note that the heading above the table says "Files (1/1)", so EGit calculated the changed files correctly, but it isn't visible. Try if resizing the window makes it appear.
The Git Staging view, which is another way to commit using EGit doesn't seem to have the same problem. Maybe you could consider using that instead of the Commit dialog, see the user guide.
As the comment 2 at the Eclipse bug 446534 mentioned, calling table.pack() will solve this problem for a single tableviewer.