If you would like to have a different mouse cursor, it's easily changed...or perhaps you've installed a different cursor, but you've noticed that the cursor will revert back to the black default cursor on certain windows/borders...
1. Install the cursor theme of your choice. You can search for
cursors in the Synaptic Package Manager or install the cursors with the Terminal if you prefer that method.
2. After installing the cursors, go to "Customize Look and Feel" in the Preferences category of the menu. Click on the Mouse Cursor tab, and click the new cursor that you want to use. Close the Look and Feel window.
Now, let's make it the default cursor...so that it shows up on all windows and borders.
3. Open your Terminal, and enter this command...sudo update-alternatives --config x-cursor-theme
You will see a list that shows all of your available cursors. To the left of each one is a number. Enter the number that coincides with the cursor that you want to use, hit Enter, and exit the Terminal.
4. Log out of your computer, and log back in...your cursor will now be the default cursor.