Add a gui.tabWidth config

Affects everything that is shown in the main view, but probably mostly relevant
for diffs.

docs/Config.md

@@ -47,6 +47,10 @@ gui:
   # One of: 'margin' (default) | 'jump'
   scrollOffBehavior: margin
 
+  # The number of spaces per tab; used for everything that's shown in the main view, but probably mostly relevant for diffs.
+  # Note that when using a pager, the pager has its own tab width setting, so you need to pass it separately in the pager command.
+  tabWidth: 4
+
   # If true, capture mouse events.
   # When mouse events are captured, it's a little harder to select text: e.g. requiring you to hold the option key when on macOS.
   mouseEvents: true

pkg/config/user_config.go

@@ -64,6 +64,9 @@ type GuiConfig struct {
 	ScrollOffMargin int `yaml:"scrollOffMargin"`
 	// One of: 'margin' (default) | 'jump'
 	ScrollOffBehavior string `yaml:"scrollOffBehavior"`
+	// The number of spaces per tab; used for everything that's shown in the main view, but probably mostly relevant for diffs.
+	// Note that when using a pager, the pager has its own tab width setting, so you need to pass it separately in the pager command.
+	TabWidth int `yaml:"tabWidth" jsonschema:"minimum=1"`
 	// If true, capture mouse events.
 	// When mouse events are captured, it's a little harder to select text: e.g. requiring you to hold the option key when on macOS.
 	MouseEvents bool `yaml:"mouseEvents"`
@@ -693,6 +696,7 @@ func GetDefaultConfig() *UserConfig {
 			ScrollPastBottom:         true,
 			ScrollOffMargin:          2,
 			ScrollOffBehavior:        "margin",
+			TabWidth:                 4,
 			MouseEvents:              true,
 			SkipDiscardChangeWarning: false,
 			SkipStashWarning:         false,

pkg/gui/views.go

@@ -203,6 +203,7 @@ func (gui *Gui) configureViewProperties() {
 
 	for _, view := range []*gocui.View{gui.Views.Main, gui.Views.Secondary, gui.Views.Staging, gui.Views.StagingSecondary, gui.Views.PatchBuilding, gui.Views.PatchBuildingSecondary, gui.Views.MergeConflicts} {
 		view.CanScrollPastBottom = gui.c.UserConfig().Gui.ScrollPastBottom
+		view.TabWidth = gui.c.UserConfig().Gui.TabWidth
 	}
 
 	gui.Views.CommitDescription.FgColor = theme.GocuiDefaultTextColor

schema/config.json

@@ -46,6 +46,12 @@
           "description": "One of: 'margin' (default) | 'jump'",
           "default": "margin"
         },
+        "tabWidth": {
+          "type": "integer",
+          "minimum": 1,
+          "description": "The number of spaces per tab; used for everything that's shown in the main view, but probably mostly relevant for diffs.\nNote that when using a pager, the pager has its own tab width setting, so you need to pass it separately in the pager command.",
+          "default": 4
+        },
         "mouseEvents": {
           "type": "boolean",
           "description": "If true, capture mouse events.\nWhen mouse events are captured, it's a little harder to select text: e.g. requiring you to hold the option key when on macOS.",