Arrrgh! I don't know why this isn't in the freaking preferences. Try to delete something in a fresh copy of iTunes, and you get a warning dialog asking, "Are you sure you want to remove the selected songs from the list?". There's a checkbox labeled "Do not ask me again". If you check that box, the warning stops... and it's gone forever. There is no mechanism for getting it back, it's gone.
Then you notice that iTunes doesn't have an "undo" feature. And that's just [expletive].
So today, after accidentally deleting my 'Vision of Escaflowne + Princess Mononoke + The Dead Zone' playlist, and painstakingly reconstructing it from an old copy on my iPod, I finally did a little scientific investigation and uncovered a procedure for restoring those warnings.
Seriously, this is just [expletive]. What a horrible thing to have to do just to restore some [expletive] warning dialogs. Anyway...
- Download and install the Xcode development tools.
- Open a finder window and click on the 'home' icon in the sidebar.
- Press command-3 to turn the window to column mode.
- Click on the Library folder, then in the next column (inside the Library folder) click on Preferences.
- Press command-2 to display this folder in list mode.
- Locate the file named "com.apple.iTunes.plist" and double-click on it. It should open in the Property List Editor, which should now be installed in Developer/Applications/Utilities on your hard drive, since you installed the Xcode tools.
- When the Property List Editor window comes up, choose File->Save As, and save the file as XML to your desktop. This removes the compression from the plist, turning it into XML text suitable for viewing in TextEdit.
- Quit the Property List Editor and open the "com.apple.iTunes.plist" file that's on your Desktop, by dragging it onto the TextEdit icon.
- Scroll down in the TextEdit window past a bunch of XML gook until you see the line "<key>pref:129:Preferences</key>", followed by the line "<data>", followed by a huge block of symbols.
- Place your cursor in the first line of this block of symbols. Now tap the down arrow once. This is line 2 of the block. This is the line you need to edit.
- Edit the 47th character of this line. Change it from an A to an E. For example,
- Place your cursor back on the first line of the block. Now press the down arrow 38 times. This should put you on line 39 of the block.
- Change the second character of this line. Change it from an A to a Q. For example,
- You're done with your edits. Save the file and quit TextEdit.
- Drag the "com.apple.iTunes.plist" file from your Desktop into the Preferences folder, replacing the old copy that's already there. Though it's uncompressed, iTunes will read it just fine.
- Open iTunes and create a blank playlist. Drag a few tracks into it. Try to delete the tracks. Note that the warning is back. Try to delete this non-empty playlist. Note that the warning is back.
- Thank [expletive] goodness. You have now just accomplished the OS X equivalent of "hacking the registry", as it is known in Windows-land.
What an [expletive] piece of [expletive] [expletive] procedure to have to [expletive] go through! Where's the "RESET ALL WARNING DIALOGS" option in the preferences, people, huh??