Fix selection on editor

src/composables/bindEditorSelection.ts

@@ -17,7 +17,7 @@ export default function bindEditorSelection(editorRef: Ref<Editor | undefined>,
     editor.selection.on('changeCursor', () => {
       const range = editor.getSelection().getRange();
       const sel = toSelection(range);
-      if (typeof selection.value == 'undefined' || !isSelectionEqual(selection.value, sel)) {
+      if (!isRangeEqual(selection.value?.origin, range) && !isSelectionEqual(selection.value, sel)) {
         selection.value = sel;
       }
     });
@@ -35,15 +35,17 @@ export default function bindEditorSelection(editorRef: Ref<Editor | undefined>,
   });
 }
 
-function toRange({ row, offset, length }: ISelection): Range {
-  return {
+function toRange({ row, offset, length, origin }: ISelection): Range {
+  return origin || {
     start: { row: row, column: offset },
     end: { row: row, column: offset + length },
   } as Range;
 }
 
-function isRangeEqual(a: Range, b: Range): boolean {
+function isRangeEqual(a: Range | undefined, b: Range | undefined): boolean {
   return (
+    typeof a != 'undefined' &&
+    typeof b != 'undefined' &&
     a.start.row == b.start.row &&
     a.start.column == b.start.column &&
     a.end.row == b.end.row &&
@@ -64,9 +66,16 @@ function toSelection(range: Range): ISelection {
     row: range.start.row,
     offset: range.start.column,
     length: range.end.column - range.start.column,
+    origin: range,
   } as ISelection;
 }
 
-function isSelectionEqual(a: ISelection, b: ISelection): boolean {
-  return a.row == b.row && a.offset == b.offset && a.length == b.length;
+function isSelectionEqual(a: ISelection | undefined, b: ISelection | undefined): boolean {
+  return (
+    typeof a != 'undefined' &&
+    typeof b != 'undefined' &&
+    a.row == b.row &&
+    a.offset == b.offset &&
+    a.length == b.length
+  );
 }

src/types/selection.ts

@@ -1,5 +1,8 @@
+import type { Range } from 'brace';
+
 export default interface ISelection {
   row: number;
   offset: number;
   length: number;
+  origin?: Range;
 }