Add support for reporting focus lost/gained (esc[?1004h enables, esc[…

…I is sent by term when focus gained, esc[O when lost, esc[?1004l disables)

Headers/iTerm/PTYSession.h

@@ -223,6 +223,9 @@ typedef enum {
 
     // The current triggers.
     NSMutableArray *triggers_;
+
+    // Does the terminal think this session is focused?
+    BOOL focused_;
 }
 
 // Return the current pasteboard value as a string.
@@ -498,6 +501,8 @@ typedef enum {
 - (void)stopCoprocess;
 - (void)launchCoprocessWithCommand:(NSString *)command;
 
+- (void)setFocused:(BOOL)focused;
+
 @end
 
 @interface PTYSession (ScriptingSupport)

Headers/iTerm/VT100Terminal.h

@@ -302,6 +302,7 @@ typedef enum {
     BOOL shouldBounceDockIcon; // YES=Bounce, NO=cancel;
     MouseMode MOUSE_MODE;
     MouseFormat MOUSE_FORMAT;
+    BOOL REPORT_FOCUS;
 
     int FG_COLORCODE;
     BOOL alternateForegroundSemantics;
@@ -379,6 +380,7 @@ typedef enum {
 - (NSData *)keypadData: (unichar) unicode keystr: (NSString *) keystr;
 
 - (char *)mouseReport:(int)button atX:(int)x Y:(int)y;
+- (BOOL)reportFocus;
 - (NSData *)mousePress:(int)button withModifiers:(unsigned int)modflag atX:(int)x Y:(int)y;
 - (NSData *)mouseReleaseWithModifiers:(unsigned int)modflag atX:(int)x Y:(int)y;
 - (NSData *)mouseMotion:(int)button withModifiers:(unsigned int)modflag atX:(int)x Y:(int)y;

PTYSession.m

@@ -3140,6 +3140,18 @@ - (void)launchCoprocessWithCommand:(NSString *)command
     [TEXTVIEW setNeedsDisplay:YES];
 }
 
+- (void)setFocused:(BOOL)focused
+{
+    if (focused != focused_) {
+        focused_ = focused;
+        if ([TERMINAL reportFocus]) {
+            char flag = focused ? 'I' : 'O';
+            NSString *message = [NSString stringWithFormat:@"%c[%c", 27, flag];
+            [self writeTask:[message dataUsingEncoding:[self encoding]]];
+        }
+    }
+}
+
 @end
 
 @implementation PTYSession (ScriptingSupport)

PTYTab.m

@@ -330,7 +330,15 @@ - (void)setActiveSessionPreservingViewOrder:(PTYSession*)session
     [self setLabelAttributes];
     [[NSNotificationCenter defaultCenter] postNotificationName:@"iTermSessionBecameKey"
                                                         object:activeSession_];
-
+    // If the active session changed in the active tab in the key window then update the
+    // focused state of all sessions in that window.
+    if ([[self realParentWindow] currentTab] == self &&
+        [[[self realParentWindow] window] isKeyWindow]) {
+      for (PTYSession *aSession in [[self realParentWindow] sessions]) {
+        [aSession setFocused:(aSession == session)];
+      }
+    }
+
     NSUInteger i = [viewOrder_ indexOfObject:[NSNumber numberWithInt:[[session view] viewId]]];
     if (i != NSNotFound) {
         currentViewIndex_ = i;

PseudoTerminal.m

@@ -1496,6 +1496,7 @@ - (void)windowDidBecomeKey:(NSNotification *)aNotification
     for (PTYSession* aSession in [self sessions]) {
         [aSession updateDisplay];
         [[aSession view] setBackgroundDimmed:NO];
+        [aSession setFocused:aSession == [self currentSession]];
     }
 }
 
@@ -1643,6 +1644,9 @@ - (void)windowDidResignKey:(NSNotification *)aNotification
             [[aSession view] setBackgroundDimmed:YES];
         }
     }
+    for (PTYSession* aSession in [self sessions]) {
+        [aSession setFocused:NO];
+    }
 }
 
 - (void)windowDidResignMain:(NSNotification *)aNotification
@@ -2357,6 +2361,11 @@ - (void)tabView:(NSTabView *)tabView didSelectTabViewItem:(NSTabViewItem *)tabVi
     // Post notifications
     [[NSNotificationCenter defaultCenter] postNotificationName:@"iTermSessionBecameKey"
                                                         object:[[tabViewItem identifier] activeSession]];
+
+    PTYSession *activeSession = [self currentSession];
+    for (PTYSession *s in [self sessions]) {
+      [aSession setFocused:(s == activeSession)];
+    }
     [self showOrHideInstantReplayBar];
 }
 

VT100Terminal.m

@@ -2235,6 +2235,10 @@ - (NSData *)mouseMotion:(int)button withModifiers:(unsigned int)modflag atX:(int
     return [NSData dataWithBytes: buf length: strlen(buf)];
 }
 
+- (BOOL)reportFocus
+{
+    return REPORT_FOCUS;
+}
 
 - (BOOL)lineMode
 {
@@ -2460,6 +2464,9 @@ - (void)_setMode:(VT100TCC)token
                     }
                     [SCREEN mouseModeDidChange:MOUSE_MODE];
                     break;
+                case 1004:
+                    REPORT_FOCUS = mode;
+                    break;
 
                 case 1005:
                     if (mode) {