Add pinned tabs

This adds the commands pin-tab and unpin-tab. Once pinned a tab lives on
the left of the tabstrip and has a configurable marker, defaulting to `
before its name.

commands/pin-tab.go

@@ -0,0 +1,36 @@
+package commands
+
+import (
+	"fmt"
+
+	"git.sr.ht/~sircmpwn/aerc/widgets"
+)
+
+type PinTab struct{}
+
+func init() {
+	register(PinTab{})
+}
+
+func (PinTab) Aliases() []string {
+	return []string{"pin-tab", "unpin-tab"}
+}
+
+func (PinTab) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (PinTab) Execute(aerc *widgets.Aerc, args []string) error {
+	if len(args) != 1 {
+		return fmt.Errorf("Usage: %s", args[0])
+	}
+
+	switch args[0] {
+	case "pin-tab":
+		aerc.PinTab()
+	case "unpin-tab":
+		aerc.UnpinTab()
+	}
+
+	return nil
+}