Wrap-around navigation among split panes.

sources/NSArray+iTerm.h

@@ -31,6 +31,9 @@
 - (BOOL)allWithBlock:(BOOL (^)(ObjectType anObject))block;
 - (ObjectType)maxWithComparator:(NSComparisonResult (^)(ObjectType a, ObjectType b))comparator;
+// All objects equal to the minimum value.
+- (NSArray *)mininumsWithComparator:(NSComparisonResult (^)(id, id))comparator;
+
 // Does the array contain at least one object not equal to @c anObject?
 - (BOOL)containsObjectBesides:(ObjectType)anObject;
 - (BOOL)containsObjectBesidesObjectsInArray:(NSArray *)array;

sources/NSArray+iTerm.m

@@ -103,6 +103,24 @@
     return max;
 }
+- (NSArray *)mininumsWithComparator:(NSComparisonResult (^)(id, id))comparator {
+    id min = nil;
+    for (id object in self) {
+        if (min == nil || comparator(min, object) == NSOrderedDescending) {
+            min = object;
+        }
+    }
+    NSMutableArray *result = [NSMutableArray array];
+    if (min) {
+        for (id object in self) {
+            if (comparator(object, min) == NSOrderedSame) {
+                [result addObject:object];
+            }
+        }
+    }
+    return result;
+}
+
 - (BOOL)anyWithBlock:(BOOL (^)(id anObject))block {
     for (id object in self) {
         if (block(object)) {

sources/PTYTab.m

@@ -1007,9 +1007,30 @@ static void SetAgainstGrainDim(BOOL isVertical, NSSize *dest, CGFloat value) {
                       verticalDir:(BOOL)verticalDir
                             after:(BOOL)after {
     NSArray<PTYSession *> *sessions = [self sessionsAdjacentToSession:session verticalDir:verticalDir after:after];
-    return [sessions maxWithComparator:^NSComparisonResult(PTYSession *a, PTYSession *b) {
-        return [a.activityCounter compare:b.activityCounter];
-    }];
+    if (sessions.count) {
+        return [sessions maxWithComparator:^NSComparisonResult(PTYSession *a, PTYSession *b) {
+            return [a.activityCounter compare:b.activityCounter];
+        }];
+    } else {
+        sessions = [self sessionsInProjectionOfSession:session verticalDirection:verticalDir after:!after];
+        NSArray<PTYSession *> *wraparounds = [sessions mininumsWithComparator:^NSComparisonResult(PTYSession *a, PTYSession *b) {
+            NSRect aRect = [root_ convertRect:a.view.frame fromView:a.view.superview];
+            NSRect bRect = [root_ convertRect:b.view.frame fromView:b.view.superview];
+            if (verticalDir) {
+                SwapSize(&aRect.size);
+                SwapPoint(&aRect.origin);
+                SwapSize(&bRect.size);
+                SwapPoint(&bRect.origin);
+            }
+
+            const CGFloat bLeft = after ? NSMinX(bRect) : -NSMaxX(bRect);
+            const CGFloat aLeft = after ? NSMinX(aRect) : -NSMaxX(aRect);
+            return [@(aLeft) compare:@(bLeft)];
+        }];
+        return [wraparounds maxWithComparator:^NSComparisonResult(PTYSession *a, PTYSession *b) {
+            return [a.activityCounter compare:b.activityCounter];
+        }];
+    }
 }
 - (PTYSession*)sessionLeftOf:(PTYSession*)session {