backends/x/event.go

@@ -69,13 +69,15 @@ func (window *Window) handleKeyPress (
 	}
 
 	if key == tomo.KeyTab && modifiers.Alt {
-		if _, ok := window.child.(tomo.Selectable); ok {
+		if child, ok := window.child.(tomo.Selectable); ok {
 			direction := tomo.SelectionDirectionForward
 			if modifiers.Shift {
 				direction = tomo.SelectionDirectionBackward
 			}
 
-			window.advanceSelectionInChild(direction)
+			if !child.HandleSelection(direction) {
+				child.HandleDeselection()
+			}
 		}
 	} else if child, ok := window.child.(tomo.KeyboardTarget); ok {
 		// FIXME: pass correct value for repeated
@@ -83,17 +85,6 @@ func (window *Window) handleKeyPress (
 	}
 }
 
-func (window *Window) advanceSelectionInChild (direction tomo.SelectionDirection) {
-	child := window.child.(tomo.Selectable)
-	if child.Selected() {
-		if !child.HandleSelection(direction) {
-			child.HandleDeselection()
-		}
-	} else {
-		child.HandleSelection(tomo.SelectionDirectionNeutral)
-	}
-}
-
 func (window *Window) handleKeyRelease (
 	connection *xgbutil.XUtil,
 	event xevent.KeyReleaseEvent,

element.go

@@ -79,6 +79,17 @@ const (
 	SelectionDirectionForward  SelectionDirection =  1
 )
 
+// Canon returns a well-formed direction.
+func (direction SelectionDirection) Canon () (canon SelectionDirection) {
+	if direction > 0 {
+		return SelectionDirectionForward
+	} else if direction == 0 {
+		return SelectionDirectionNeutral
+	} else {
+		return SelectionDirectionBackward
+	}
+}
+
 // Selectable represents an element that has keyboard navigation support. This
 // includes inputs, buttons, sliders, etc. as well as any elements that have
 // children (so keyboard navigation events can be propagated downward).

elements/basic/button.go

@@ -103,16 +103,17 @@ func (element *Button) HandleSelection (
 ) (
 	accepted bool,
 ) {
-	if direction == tomo.SelectionDirectionNeutral && element.enabled {
+	if !element.enabled { return false }
-		element.selected = true
+	if element.selected && direction != tomo.SelectionDirectionNeutral {
-		if element.core.HasImage() {
-			element.draw()
-			element.core.PushAll()
-		}
-		return true
-	} else {
 		return false
 	}
+	
+	element.selected = true
+	if element.core.HasImage() {
+		element.draw()
+		element.core.PushAll()
+	}
+	return true
 }
 
 func (element *Button) HandleDeselection () {

elements/basic/container.go

@@ -244,44 +244,41 @@ func (element *Container) Select () {
 // FIXME
 func (element *Container) HandleSelection (direction tomo.SelectionDirection) (ok bool) {
 	if !element.selectable { return false }
+	direction = direction.Canon()
 
 	firstSelected := element.firstSelected()
 	if firstSelected < 0 {
+		found := false
 		switch direction {
-		case tomo.SelectionDirectionNeutral,
+		case tomo.SelectionDirectionBackward:
-		tomo.SelectionDirectionBackward:
 			element.forSelectableBackward (func (child tomo.Selectable) bool {
-				if child.HandleSelection (
+				if child.HandleSelection(direction) {
-					tomo.SelectionDirectionNeutral,
-				) {
 					element.selected = true
+					found = true
 					return false
 				}
 				return true
 			})
+			return true
 		
-		case tomo.SelectionDirectionForward:
+		case tomo.SelectionDirectionNeutral, tomo.SelectionDirectionForward:
 			element.forSelectable (func (child tomo.Selectable) bool {
-				if child.HandleSelection (
+				if child.HandleSelection(direction) {
-					tomo.SelectionDirectionNeutral,
-				) {
 					element.selected = true
+					found = true
 					return false
 				}
 				return true
 			})
 		}
-
+		return found
-		return false
 	} else {
 		firstSelectedChild :=
 			element.children[firstSelected].Element.(tomo.Selectable)
-		step := 1
-		if direction < 0 { step = - 1 }
 		
-		for index := firstSelected + step;
+		for index := firstSelected + int(direction);
 			index < len(element.children) && index >= 0;
-			index += step {
+			index += int(direction) {
 
 			child, selectable :=
 				element.children[index].
@@ -294,7 +291,7 @@ func (element *Container) HandleSelection (direction tomo.SelectionDirection) (o
 		}
 	}
 	
-	return
+	return false
 }
 
 func (element *Container) HandleDeselection () {