Attempt to fix #1961

Namely this commit changes two things:
1) In the past the user manager window technically was closed after it was released (SPUserManager.m:491):

    [NSApp endSheet:[self window] returnCode:0]; //-> calls delegate,  which calls release
    [[self window] orderOut:self];

This call order has now been swapped.
2) Because the delegate is invoked directly by NSApp, the release was called before other UI elements had finished their cleanup from orderOut:. The delegate callback is now put on the runloop to give other stuff priority.

Requesting QA on this commit.

Author: dmoagx

Source/SPDatabaseDocument.h

@@ -427,7 +427,6 @@
 
 - (void)saveConnectionPanelDidEnd:(NSSavePanel *)panel returnCode:(NSInteger)returnCode  contextInfo:(void  *)contextInfo;
 - (BOOL)saveDocumentWithFilePath:(NSString *)fileName inBackground:(BOOL)saveInBackground onlyPreferences:(BOOL)saveOnlyPreferences contextInfo:(NSDictionary*)contextInfo;
-- (void)userManagerSheetDidEnd:(NSWindow *)sheet returnCode:(int)returnCode contextInfo:(void*)context;
 - (void)setIsSavedInBundle:(BOOL)savedInBundle;
 - (void)setFileURL:(NSURL *)fileURL;
 - (void)connect;

Source/SPDatabaseDocument.m

@@ -2483,16 +2483,10 @@ - (IBAction)showUserManager:(id)sender
 		return;
 	}
 
-	[NSApp beginSheet:[userManagerInstance window]
-	   modalForWindow:parentWindow 
-		modalDelegate:self 
-	   didEndSelector:@selector(userManagerSheetDidEnd:returnCode:contextInfo:)
-		  contextInfo:nil];
-}
-
-- (void)userManagerSheetDidEnd:(NSWindow *)sheet returnCode:(int)returnCode contextInfo:(void*)context
-{
-	[userManagerInstance release], userManagerInstance = nil;
+	[userManagerInstance beginSheetModalForWindow:parentWindow
+								completionHandler:^(){
+		[userManagerInstance release], userManagerInstance = nil;
+	}];
 }
 
 /**

Source/SPUserManager.h

@@ -124,4 +124,12 @@
 - (BOOL)grantPrivilegesToUser:(NSManagedObject *)user;
 - (BOOL)grantDbPrivilegesWithPrivilege:(NSManagedObject *)user;
 
+// External
+/**
+ * Display the user manager as a sheet attached to a chosen window
+ * @param docWindow The parent window.
+ * @param callback  A callback that will be called once the window is closed again. Can be NULL.
+ */
+- (void)beginSheetModalForWindow:(NSWindow *)docWindow completionHandler:(void (^)())callback;
+
 @end

Source/SPUserManager.m

@@ -61,6 +61,7 @@ - (NSArray *)_fetchPrivsWithUser:(NSString *)username schema:(NSString *)selecte
 - (void)_setSchemaPrivValues:(NSArray *)objects enabled:(BOOL)enabled;
 - (void)_initializeAvailablePrivs;
 - (void)_renameUserFrom:(NSString *)originalUser host:(NSString *)originalHost to:(NSString *)newUser host:(NSString *)newHost;
+- (void)sheetDidEnd:(NSWindow *)sheet returnCode:(int)returnCode contextInfo:(void*)context;
 
 @end
 
@@ -471,6 +472,31 @@ - (NSManagedObjectContext *)managedObjectContext
     return managedObjectContext;
 }
 
+- (void)beginSheetModalForWindow:(NSWindow *)docWindow completionHandler:(void (^)())callback
+{
+	//copy block from stack to heap, otherwise it wouldn't live long enough to be invoked later.
+	void *heapCallback = callback? Block_copy(callback) : NULL;
+	
+	[NSApp beginSheet:[self window]
+	   modalForWindow:docWindow
+		modalDelegate:self
+	   didEndSelector:@selector(sheetDidEnd:returnCode:contextInfo:)
+		  contextInfo:heapCallback];
+}
+
+- (void)sheetDidEnd:(NSWindow *)sheet returnCode:(int)returnCode contextInfo:(void*)context
+{
+	//[NSApp endSheet...] does not close the window
+	[[self window] orderOut:self];
+	//notify delegate
+	if(context) {
+		void (^callback)() = context;
+		//directly invoking callback would risk that we are dealloc'd while still in this run loop iteration.
+		dispatch_async(dispatch_get_main_queue(), callback);
+		Block_release(callback);
+	}
+}
+
 #pragma mark -
 #pragma mark General IBAction methods
 
@@ -489,7 +515,6 @@ - (IBAction)doCancel:(id)sender
 
 	// Close sheet
 	[NSApp endSheet:[self window] returnCode:0];
-	[[self window] orderOut:self];
 }
 
 /**
@@ -539,7 +564,6 @@ - (IBAction)doApply:(id)sender
 
 	// Otherwise, close the sheet
 	[NSApp endSheet:[self window] returnCode:0];
-	[[self window] orderOut:self];
 }
 
 /**