#93: drive the research menu with a mouse, and close the hole under it

Two separate faults, both reported on the same ticket.

The menu was inert under a mouse. Input reaches the tree as raw events
through BuildController._unhandled_input, because a Control that consumes
them through the GUI system swallows the drag, and the tree only ever read
touch events. That was invisible while the project set
emulate_touch_from_mouse and every click arrived as a synthetic touch; with
that setting gone, nothing selects and nothing scrolls, and there is no
other way to research anything on a desktop. The press and the pan are now
the behaviour, with touch and mouse as two ways in to them. Motion pans only
while the button is held - a hovering pointer must not drag the tree out
from under the reader - and the wheel scrolls, which is the first thing a
desktop player reaches for.

The panel also still had the buy button's hole in it. That button went away
in #83 and nothing moved down into the space, leaving ~180px of dead panel
below the readout while the tree above it stayed cramped. The readout moves
down 154px and the canvas takes the height: 1190px to 1344px.

The test drives clicks through BuildController rather than into the view,
since the missing piece was the routing - calling the view directly would
have passed against the bug as reported.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_skill_menu.gd

@@ -0,0 +1,181 @@
+extends SceneTree
+
+# Headless test: run with
+#   godot --headless -s res://tests/test_skill_menu.gd
+# Forgejo #93, both halves of it.
+#
+#   A mouse could not drive the research menu at all. Input reaches the tree
+#   through BuildController._unhandled_input as raw events (a Control that
+#   eats them through the GUI system would swallow the drag - see
+#   SkillTreeView's header), and the tree only ever read touch events. That
+#   was invisible for as long as the project set emulate_touch_from_mouse,
+#   which handed it a synthetic touch per click; with that setting gone, the
+#   menu is inert under a mouse and there is no other way to research
+#   anything on a desktop.
+#
+#   The panel also still had a hole in it. The buy button below the readout
+#   went away in #83, and nothing moved into the space, so ~180px of empty
+#   panel sat under the text while the tree canvas above it stayed cramped.
+#
+# Covers:
+#   A. a left click selects a node, through the real routing in
+#      BuildController rather than by calling the view directly
+#   B. a second click on the SAME node researches it, which is #83's
+#      confirm gesture reached with a mouse
+#   C. holding the left button and moving scrolls the canvas, and moving
+#      with no button held does NOT - a hovering pointer must not drag the
+#      tree out from under the reader
+#   D. the wheel scrolls, in both directions
+#   E. the readout sits at the bottom of the panel and the tree canvas fills
+#      everything above it, so neither the dead band nor the cramped tree
+#      comes back
+
+const GAP_TOLERANCE: float = 48.0
+
+var game_state: Node
+var scene: Node
+var controller: Node
+var skill_menu: Control
+var tree_view: Control
+var stage: int = 0
+var elapsed: float = 0.0
+
+
+func _initialize() -> void:
+	game_state = root.get_node("GameState")
+	game_state.buildings.clear()
+	game_state.extractors.clear()
+	game_state.reset_progression()
+	game_state.reset_formation()
+	game_state.rocks = 500
+
+	scene = load("res://world/Main.tscn").instantiate()
+	root.add_child(scene)
+	controller = scene.get_node("BuildController")
+	skill_menu = scene.get_node("UI/SkillMenu")
+	tree_view = scene.get_node("UI/SkillMenu/Tree")
+
+
+func _click(at: Vector2, pressed: bool) -> void:
+	var event: InputEventMouseButton = InputEventMouseButton.new()
+	event.button_index = MOUSE_BUTTON_LEFT
+	event.pressed = pressed
+	event.position = at
+	# Through the controller, not straight into the view: the missing piece
+	# was the ROUTING, so a test that called tree_view.handle_mouse_button()
+	# itself would have passed against the reported bug.
+	controller._unhandled_input(event)
+
+
+func _wheel(button: int) -> void:
+	var event: InputEventMouseButton = InputEventMouseButton.new()
+	event.button_index = button
+	event.pressed = true
+	event.position = tree_view.global_position + tree_view.size * 0.5
+	controller._unhandled_input(event)
+
+
+func _move(relative: Vector2) -> void:
+	var event: InputEventMouseMotion = InputEventMouseMotion.new()
+	event.relative = relative
+	event.position = tree_view.global_position + tree_view.size * 0.5
+	controller._unhandled_input(event)
+
+
+func _node_at(id: String) -> Vector2:
+	return tree_view.global_position + tree_view.node_screen_pos(game_state.skill_node(id))
+
+
+func _process(delta: float) -> bool:
+	elapsed += delta
+	if stage == 0:
+		scene.get_node("AsteroidField").set_process(false)
+		scene.get_node("EnemySpawner").set_process(false)
+		scene.get_node("BuildingField").place(GameState.BUILDING_MOTHERSHIP, Vector2(400.0, 0.0))
+		elapsed = 0.0
+		stage = 1
+		return false
+	if stage != 1 or elapsed < 0.2:
+		return false
+	stage = 2
+
+	var mothership: Node2D = null
+	for building in scene.get_node("BuildingField").spawned:
+		if is_instance_valid(building) and building.building_type == GameState.BUILDING_MOTHERSHIP:
+			mothership = building
+	controller.current_building = mothership
+	controller._on_action_pressed()
+	if not skill_menu.visible:
+		return _fail("the mothership did not open the research menu")
+
+	# --- A. a click selects --------------------------------------------
+	var shipyards: Vector2 = _node_at("shipyards")
+	_click(shipyards, true)
+	if tree_view.selected_id != "shipyards":
+		return _fail("a left click on a node selected \"%s\" instead of it" % tree_view.selected_id)
+	_click(shipyards, false)
+	print("a left click selects the node under it")
+
+	# --- B. a second click researches ----------------------------------
+	if game_state.is_unlocked("shipyards"):
+		return _fail("shipyards was already researched, so the confirm proves nothing")
+	_click(shipyards, true)
+	_click(shipyards, false)
+	if not game_state.is_unlocked("shipyards"):
+		return _fail("a second click on the selected node did not research it")
+	print("a second click on the same node researches it")
+
+	# --- C. held drag scrolls, a bare hover does not --------------------
+	var before: float = tree_view.scroll_y
+	_move(Vector2(0.0, 120.0))
+	if not is_equal_approx(tree_view.scroll_y, before):
+		return _fail("the tree scrolled under a hovering pointer with no button held")
+	_click(_node_at("shipyards"), true)
+	_move(Vector2(0.0, 120.0))
+	var dragged: float = tree_view.scroll_y
+	if dragged >= before:
+		return _fail("holding the button and moving did not scroll the tree (%f -> %f)" \
+			% [before, dragged])
+	_click(_node_at("shipyards"), false)
+	_move(Vector2(0.0, 120.0))
+	if not is_equal_approx(tree_view.scroll_y, dragged):
+		return _fail("the tree kept scrolling after the button was released")
+	print("drag scrolls only while the button is held: %.0f -> %.0f" % [before, dragged])
+
+	# --- D. the wheel scrolls ------------------------------------------
+	_wheel(MOUSE_BUTTON_WHEEL_UP)
+	var wheeled: float = tree_view.scroll_y
+	if wheeled >= dragged:
+		return _fail("the wheel did not scroll the tree upward")
+	_wheel(MOUSE_BUTTON_WHEEL_DOWN)
+	if tree_view.scroll_y <= wheeled:
+		return _fail("the wheel did not scroll back down")
+	print("the wheel scrolls both ways")
+
+	# --- E. the panel has no dead band at the bottom --------------------
+	var detail: Control = scene.get_node("UI/SkillMenu/DetailLabel")
+	var status: Control = scene.get_node("UI/SkillMenu/StatusLabel")
+	var tree_bottom: float = tree_view.position.y + tree_view.size.y
+	var readout_gap: float = detail.position.y - tree_bottom
+	var floor_gap: float = skill_menu.size.y - (status.position.y + status.size.y)
+	print("tree %.0fpx tall, %.0fpx to the readout, %.0fpx of panel below it" \
+		% [tree_view.size.y, readout_gap, floor_gap])
+	if tree_view.size.y <= 0.0:
+		return _fail("the tree canvas has no height")
+	if readout_gap < 0.0:
+		return _fail("the tree canvas overlaps the readout below it")
+	if readout_gap > GAP_TOLERANCE:
+		return _fail("%.0fpx of unused panel between the tree and the readout" % readout_gap)
+	if floor_gap > GAP_TOLERANCE:
+		return _fail("%.0fpx of dead panel below the readout - the removed buy button's hole" \
+			% floor_gap)
+
+	print("TEST_SKILL_MENU: PASS")
+	quit(0)
+	return true
+
+
+func _fail(message: String) -> bool:
+	print("TEST_SKILL_MENU: FAIL (%s)" % message)
+	quit(1)
+	return true