Store the preferred width of the left tab bar separately from its actual...

Store the preferred width of the left tab bar separately from its actual width, which is constrained by the width of the window. The preferred width is set by a manual drag and is persisted in user defaults. When the window is wide enough to accommodate the preferred width, the tab bar will grow up to but not beyond that size. Issue 5833

sources/iTermRootTerminalView.m

@@ -30,6 +30,8 @@ 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
@@ -47,7 +49,9 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
         _delegate = delegate;
         self.autoresizesSubviews = YES;
-        _leftTabBarWidth = [iTermPreferences doubleForKey:kPreferenceKeyLeftTabBarWidth];
+        _leftTabBarPreferredWidth = [iTermPreferences doubleForKey:kPreferenceKeyLeftTabBarWidth];
+        [self setLeftTabBarWidthFromPreferredWidth];
+        
         // Create the tab view.
         self.tabView = [[[PTYTabView alloc] initWithFrame:self.bounds] autorelease];
         _tabView.autoresizingMask = (NSViewWidthSizable | NSViewHeightSizable);
@@ -352,7 +356,7 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
             }
             case PSMTab_LeftTab: {
-                [self constrainLeftTabBarWidth];
+                [self setLeftTabBarWidthFromPreferredWidth];
                 CGFloat heightAdjustment = 0;
                 if (_delegate.haveBottomBorder) {
                     heightAdjustment += 1;
@@ -434,14 +438,14 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
     DLog(@"repositionWidgets - return.");
 }
-- (void)constrainLeftTabBarWidth {
-    if (_leftTabBarWidth < 50) {
-        _leftTabBarWidth = 50;
-    }
-    const CGFloat maxWidth = self.bounds.size.width / 3;
-    if (_leftTabBarWidth > maxWidth) {
-        _leftTabBarWidth = maxWidth;
-    }
+- (CGFloat)leftTabBarWidthForPreferredWidth:(CGFloat)preferredWidth {
+    const CGFloat minimumWidth = 50;
+    const CGFloat maximumWidth = self.bounds.size.width / 3;
+    return  MAX(MIN(maximumWidth, preferredWidth), minimumWidth);
+}
+
+- (void)setLeftTabBarWidthFromPreferredWidth {
+    _leftTabBarWidth = [self leftTabBarWidthForPreferredWidth:_leftTabBarPreferredWidth];
 }
 #pragma mark - iTermTabBarControlViewDelegate
@@ -462,12 +466,12 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
 // For the left-side tab bar.
 - (CGFloat)dragHandleView:(iTermDragHandleView *)dragHandle didMoveBy:(CGFloat)delta {
-    CGFloat originalValue = _leftTabBarWidth;
-    _leftTabBarWidth += delta;
+    CGFloat originalValue = _leftTabBarPreferredWidth;
+    _leftTabBarPreferredWidth = [self leftTabBarWidthForPreferredWidth:_leftTabBarPreferredWidth + delta];
     [self layoutSubviews];  // This may modify _leftTabBarWidth if it's too big or too small.
-    [[NSUserDefaults standardUserDefaults] setDouble:_leftTabBarWidth
+    [[NSUserDefaults standardUserDefaults] setDouble:_leftTabBarPreferredWidth
                                               forKey:kPreferenceKeyLeftTabBarWidth];
-    return _leftTabBarWidth - originalValue;
+    return _leftTabBarPreferredWidth - originalValue;
 }
 - (void)dragHandleViewDidFinishMoving:(iTermDragHandleView *)dragHandle {