InputHandler // Allow moving cursor in candidate state.

- The hotkey is (Shift+)Opt+FWD/BWD.

Packages/vChewing_MainAssembly/Sources/MainAssembly/InputHandler_HandleCandidate.swift

@@ -150,6 +150,42 @@ extension InputHandler {
         _ = ctlCandidate.showPreviousPage() ? {}() : delegate.callError("9569955D")
         return true
       case .kUpArrow, .kDownArrow, .kLeftArrow, .kRightArrow:
+        switch input.commonKeyModifierFlags {
+        case [.option, .shift] where input.isCursorForward:
+          if compositor.cursor < compositor.length {
+            compositor.cursor += 1
+            if isCursorCuttingChar() { compositor.jumpCursorBySpan(to: .front) }
+            delegate.switchState(generateStateOfCandidates())
+          } else {
+            delegate.callError("D3006C85")
+          }
+          return true
+        case [.option, .shift] where input.isCursorBackward:
+          if compositor.cursor > 0 {
+            compositor.cursor -= 1
+            if isCursorCuttingChar() { compositor.jumpCursorBySpan(to: .rear) }
+            delegate.switchState(generateStateOfCandidates())
+          } else {
+            delegate.callError("DE9DAF0D")
+          }
+          return true
+        case .option where input.isCursorForward:
+          if compositor.cursor < compositor.length {
+            compositor.jumpCursorBySpan(to: .front)
+            delegate.switchState(generateStateOfCandidates())
+          } else {
+            delegate.callError("5D9F4819")
+          }
+          return true
+        case .option where input.isCursorBackward:
+          if compositor.cursor > 0 {
+            compositor.jumpCursorBySpan(to: .rear)
+            delegate.switchState(generateStateOfCandidates())
+          } else {
+            delegate.callError("34B6322D")
+          }
+          return true
+        default:
           handleArrowKey: switch (keyCodeType, ctlCandidate.currentLayout) {
           case (.kLeftArrow, .horizontal), (.kUpArrow, .vertical): // Previous Candidate
             _ = ctlCandidate.highlightPreviousCandidate()
@@ -161,6 +197,8 @@ extension InputHandler {
             _ = ctlCandidate.showNextLine()
           default: break handleArrowKey
           }
+          return true
+        }
       case .kHome:
         _ =
           (ctlCandidate.highlightedIndex == 0)