Validating fonts and colors NSToolbarItem items - objective-c

Question

Using Cocoa with latest SDK on OSX 10.6.6
I have an NSToolbar with custom toolbar items and also the built in fonts and colors NSToolbarItem items (NSToolbarShowFontsItem and NSToolbarShowColorsItem identifiers).
I need to be able to enable/disable those in various situations. Problem is validateToolbarItem: is never called for these items (it is being called for my other toolbar items).
The documentation is not very clear about this:
The toolbar automatically takes care
of darkening an image item when it is
clicked and fading it when it is
disabled. All your code has to do is
validate the item. If an image item
has a valid target/action pair, then
the toolbar will call
NSToolbarItemValidation’s
validateToolbarItem: on target if the
target implements it; otherwise the
item is enabled by default.
I don't explicitly set target/action for these two toolbar items, I want to use their default behavior. Does it mean I can't validate these items? Or is there any other way I can do this?
Thanks.

Answer 1

After some trial and error, I think I was able to figure this out and find a reasonable workaround. I will post a quick answer here for future reference for others facing the same problem.
This is just one more of Cocoa's design flaws. NSToolbar has a hardcoded behavior to set the target/action for NSToolbarShowFontsItem and NSToolbarShowColorsItem to NSApplication so as the documentation hints it will never invoke validateToolbarItem: for these NSToolbarItem items.
If you need those toolbar items validated, the trivial thing to do is not to use the default fonts/colors toolbar items but to roll your own, calling the same NSApplication actions (see below).
If using the default ones, it is possible to redirect the target/action of them to your object and then invoke the original actions
- (void) toolbarWillAddItem:(NSNotification *)notification {
NSToolbarItem *addedItem = [[notification userInfo] objectForKey: #"item"];
if([[addedItem itemIdentifier] isEqual: NSToolbarShowFontsItemIdentifier]) {
[addedItem setTarget:self];
[addedItem setAction:#selector(toolbarOpenFontPanel:)];
} else if ([[addedItem itemIdentifier] isEqual: NSToolbarShowColorsItemIdentifier]) {
[addedItem setTarget:self];
[addedItem setAction:#selector(toolbarOpenColorPanel:)];
}
}
Now validateToolbarItem: will be called:
- (BOOL)validateToolbarItem:(NSToolbarItem *)theItem {
//validate item here
}
And here are the actions that will be invoked:
-(IBAction)toolbarOpenFontPanel:(id)sender {
[NSApp orderFrontFontPanel:sender];
}
-(IBAction)toolbarOpenColorPanel:(id)sender {
[NSApp orderFrontColorPanel:sender];
}
I guess the engineers who designed this never thought one would want to validate fonts/colors toolbar items. Go figure.