Clear cursors before performing undo or redo

This fix isn't ideal because it removes the cursors but it does work

Fixes #798

cmd/micro/actions.go

@@ -996,6 +996,10 @@ func (v *View) Undo(usePlugin bool) bool {
 		return false
 	}
 
+	if v.Buf.curCursor == 0 {
+		v.Buf.clearCursors()
+	}
+
 	v.Buf.Undo()
 	messenger.Message("Undid action")
 
@@ -1011,6 +1015,10 @@ func (v *View) Redo(usePlugin bool) bool {
 		return false
 	}
 
+	if v.Buf.curCursor == 0 {
+		v.Buf.clearCursors()
+	}
+
 	v.Buf.Redo()
 	messenger.Message("Redid action")
 
@@ -2028,12 +2036,7 @@ func (v *View) RemoveAllMultiCursors(usePlugin bool) bool {
 			return false
 		}
 
-		for i := 1; i < len(v.Buf.cursors); i++ {
-			v.Buf.cursors[i] = nil
-		}
-		v.Buf.cursors = v.Buf.cursors[:1]
-		v.Buf.UpdateCursors()
-		v.Cursor.ResetSelection()
+		v.Buf.clearCursors()
 		v.Relocate()
 
 		if usePlugin {

cmd/micro/buffer.go

@@ -562,3 +562,12 @@ func (b *Buffer) ClearMatches() {
 		b.SetState(i, nil)
 	}
 }
+
+func (b *Buffer) clearCursors() {
+	for i := 1; i < len(b.cursors); i++ {
+		b.cursors[i] = nil
+	}
+	b.cursors = b.cursors[:1]
+	b.UpdateCursors()
+	b.Cursor.ResetSelection()
+}

cmd/micro/view.go

@@ -479,9 +479,14 @@ func (v *View) ExecuteActions(actions []func(*View, bool) bool) bool {
 	return relocate
 }
 
-func (v *View) SetCursor(c *Cursor) {
+func (v *View) SetCursor(c *Cursor) bool {
+	if c == nil {
+		return false
+	}
 	v.Cursor = c
 	v.Buf.curCursor = c.Num
+
+	return true
 }
 
 // HandleEvent handles an event passed by the main loop
@@ -505,7 +510,10 @@ func (v *View) HandleEvent(event tcell.Event) {
 				}
 				if e.Modifiers() == key.modifiers {
 					for _, c := range v.Buf.cursors {
-						v.SetCursor(c)
+						ok := v.SetCursor(c)
+						if !ok {
+							break
+						}
 						relocate = false
 						isBinding = true
 						relocate = v.ExecuteActions(actions) || relocate
@@ -553,7 +561,6 @@ func (v *View) HandleEvent(event tcell.Event) {
 			for _, c := range v.Buf.cursors {
 				v.SetCursor(c)
 				v.paste(e.Text())
-
 			}
 			v.SetCursor(&v.Buf.Cursor)
 
@@ -568,7 +575,10 @@ func (v *View) HandleEvent(event tcell.Event) {
 		for key, actions := range bindings {
 			if button == key.buttons && e.Modifiers() == key.modifiers {
 				for _, c := range v.Buf.cursors {
-					v.SetCursor(c)
+					ok := v.SetCursor(c)
+					if !ok {
+						break
+					}
 					relocate = v.ExecuteActions(actions) || relocate
 				}
 				v.SetCursor(&v.Buf.Cursor)