Fix a problem where second and later tabs in a window with a left-side tab bar...

Fix a problem where second and later tabs in a window with a left-side tab bar that's limited by the 1/3 * content size bound will have fewer columns than it should. Issue 6371.

sources/PseudoTerminal.m

@@ -4427,10 +4427,12 @@ ITERM_WEAKLY_REFERENCEABLE
         [session setIgnoreResizeNotifications:NO];
     }
+    const BOOL willShowTabBar = ([iTermPreferences boolForKey:kPreferenceKeyHideTabBar] &&
+                                 [_contentView.tabView numberOfTabViewItems] > 1 &&
+                                 [_contentView.tabBarControl isHidden]);
     // check window size in case tabs have to be hidden or shown
     if (([_contentView.tabView numberOfTabViewItems] == 1) ||  // just decreased to 1 or increased above 1 and is hidden
-        ([iTermPreferences boolForKey:kPreferenceKeyHideTabBar] &&
-         ([_contentView.tabView numberOfTabViewItems] > 1 && [_contentView.tabBarControl isHidden]))) {
+        willShowTabBar) {
         // Need to change the visibility status of the tab bar control.
         PtyLog(@"tabViewDidChangeNumberOfTabViewItems - calling fitWindowToTab");
@@ -4449,6 +4451,9 @@ ITERM_WEAKLY_REFERENCEABLE
             PTYSession *session = firstTab.sessions.firstObject;
             [[session view] setShowTitle:NO adjustScrollView:YES];
         }
+        if (willShowTabBar && [iTermPreferences intForKey:kPreferenceKeyTabPosition] == PSMTab_LeftTab) {
+            [_contentView willShowTabBar];
+        }
         [self fitWindowToTabs];
         [self repositionWidgets];
         if (wasDraggedFromAnotherWindow_) {

sources/iTermRootTerminalView.h

@@ -69,6 +69,7 @@ extern const CGFloat kHorizontalTabBarHeight;
 @property(nonatomic, readonly) CGFloat tabviewWidth;
 @property(nonatomic, readonly) CGFloat leftTabBarWidth;
+@property(nonatomic, readonly) CGFloat leftTabBarPreferredWidth;
 - (instancetype)initWithFrame:(NSRect)frame
                         color:(NSColor *)color
@@ -93,4 +94,6 @@ extern const CGFloat kHorizontalTabBarHeight;
 - (BOOL)tabBarShouldBeVisibleWithAdditionalTabs:(int)numberOfAdditionalTabs;
+- (void)willShowTabBar;
+
 @end

sources/iTermRootTerminalView.m

@@ -30,7 +30,6 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
 @property(nonatomic, retain) SolidColorView *divisionView;
 @property(nonatomic, retain) iTermToolbeltView *toolbelt;
 @property(nonatomic, retain) iTermDragHandleView *leftTabBarDragHandle;
-@property(nonatomic, readonly) CGFloat leftTabBarPreferredWidth;
 @end
@@ -293,6 +292,10 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
         DLog(@"repositionWidgets - Set tab view frame to %@", NSStringFromRect(tabViewFrame));
         [self.tabView setFrame:tabViewFrame];
         [self updateDivisionView];
+
+        // Even though it's not visible it needs an accurate number so we can compute the proper
+        // window size when it appears.
+        [self setLeftTabBarWidthFromPreferredWidth];
     } else {
         // The tabBar control is visible.
         DLog(@"repositionWidgets - tabs are visible. Adjusting window size...");
@@ -451,16 +454,33 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
     DLog(@"repositionWidgets - return.");
 }
-- (CGFloat)leftTabBarWidthForPreferredWidth:(CGFloat)preferredWidth {
+- (CGFloat)leftTabBarWidthForPreferredWidth:(CGFloat)preferredWidth contentWidth:(CGFloat)contentWidth {
     const CGFloat minimumWidth = 50;
-    const CGFloat maximumWidth = self.bounds.size.width / 3;
-    return  MAX(MIN(maximumWidth, preferredWidth), minimumWidth);
+    const CGFloat maximumWidth = contentWidth / 3;
+    return MAX(MIN(maximumWidth, preferredWidth), minimumWidth);
+}
+
+- (CGFloat)leftTabBarWidthForPreferredWidth:(CGFloat)preferredWidth {
+    return [self leftTabBarWidthForPreferredWidth:preferredWidth contentWidth:self.bounds.size.width];
 }
 - (void)setLeftTabBarWidthFromPreferredWidth {
     _leftTabBarWidth = [self leftTabBarWidthForPreferredWidth:_leftTabBarPreferredWidth];
 }
+- (void)willShowTabBar {
+    const CGFloat minimumWidth = 50;
+    // Given that the New window width (N) = Tab bar width (T) + Content Size (C)
+    // Given that T < N/3 (by leftTabBarWidthForPreferredWidth):
+    // T <= N / 3
+    // T <= 1/3(T+C)
+    // T <= T/3 + C/3
+    // 2/3T <= C/3
+    // T <= C/2
+    const CGFloat maximumWidth = self.bounds.size.width / 2;
+    _leftTabBarWidth = MAX(MIN(maximumWidth, _leftTabBarPreferredWidth), minimumWidth);
+}
+
 #pragma mark - iTermTabBarControlViewDelegate
 - (BOOL)iTermTabBarShouldFlashAutomatically {