macosx: delay the 'rebuilding fontcache' dialog (close #6040)

(cherry picked from commit 5b459832)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/macosx/coredialogs.h

@@ -87,6 +87,7 @@
 -(void)showLoginDialog: (NSValue *)o_value;
 -(IBAction)loginDialogAction:(id)sender;
 
+-(void)showProgressDialogOnMainThread: (NSValue *)o_value;
 -(void)showProgressDialog: (NSValue *)o_value;
 -(IBAction)progDialogAction:(id)sender;
 -(BOOL)progressCancelled;

modules/gui/macosx/coredialogs.m

@@ -79,7 +79,7 @@ static VLCCoreDialogProvider *_o_sharedInstance = nil;
     else if( [o_type isEqualToString: @"dialog-login"] )
         [self performSelectorOnMainThread:@selector(showLoginDialog:) withObject:o_value waitUntilDone:YES];
     else if( [o_type isEqualToString: @"dialog-progress-bar"] )
-        [self performSelectorOnMainThread:@selector(showProgressDialog:) withObject:o_value waitUntilDone:YES];
+        [self performSelector:@selector(showProgressDialogOnMainThread:) withObject: o_value afterDelay:3.00];
     else
         msg_Err( VLCIntf, "unhandled dialog type: '%s'", type );
 }
@@ -161,6 +161,14 @@ static VLCCoreDialogProvider *_o_sharedInstance = nil;
         [NSApp stopModalWithCode: 0];
 }
 
+-(void)showProgressDialogOnMainThread: (NSValue *)o_value
+{
+    /* we work-around a Cocoa limitation here, since you cannot delay an execution
+     * on the main thread within a single call */
+    if (VLCIntf)
+        [self performSelectorOnMainThread:@selector(showProgressDialog:) withObject:o_value waitUntilDone:YES];
+}
+
 -(void)showProgressDialog: (NSValue *)o_value
 {
     dialog_progress_bar_t *p_dialog = [o_value pointerValue];