GUIs, keys and tooltips

All input goes through vanilla's own MouseHandler and KeyboardHandler, so screens, widgets and keybinds (yours and other mods') react as they do to a real player.

Reading a screen

mc_snapshot lists the open screen's class and title, its widgets and, for container screens, every slot:

• Widgets have a stable id like 3:Button:Done (index, class, text), plus type, text, position and size, and whether they are active, focused and visible.
• Slots have their menu index, item, count, components and position, and the snapshot includes the carried stack.

Coordinates are GUI-scaled, the same space the screen's own code uses.

Clicking

• mc_click_widget {id} clicks a widget's centre. Prefer it over raw coordinates: it fails clearly if the widget is missing, hidden or inactive.
• mc_click {x, y, button?, modifiers?} clicks anywhere.
• mc_click_slot {index, button?, clickType?} is a container click by menu slot index. clickType is one of PICKUP (default), QUICK_MOVE (shift-click), SWAP, CLONE, THROW, QUICK_CRAFT, PICKUP_ALL.
• mc_hover {slot} or mc_hover {x, y} moves the mouse without clicking, so a screenshot shows the hovered slot's tooltip or a widget's hover state.
• mc_scroll {amount, x?, y?} scrolls lists, or the hotbar in-world.

Keys and text

• mc_key {key} taps a key: e, escape, enter, tab, f3, left_shift, up, … Add modifiers for shortcuts, such as {key: "a", modifiers: ["ctrl"]}.
• mc_type {text} types into the focused text field.
• mc_keybind {name, action, ticks?} drives any key mapping by name, including other mods' keybinds, and can hold it for a number of ticks. Walking is holding forward. mc_keybinds lists them all.

Keybind actions apply on the next tick

mc_key {key: "e"} returns before the inventory opens. Follow it with mc_wait_for {condition: "screen:InventoryScreen"}.

Holding Shift, Ctrl or Alt

Many mods show extra lines only while a modifier is held ("Hold Shift for details"), or change behaviour while it is. They check with Minecraft.hasShiftDown() / hasControlDown() / hasAltDown(), which read the real keyboard state. MCTest makes the keys it holds count as down for those checks too.

Just the tooltip text:

mc_tooltip {"slot": 0, "modifiers": ["shift"]}

Shift is held only while the tooltip is built. slot is the menu slot index when a container screen is open, otherwise a player inventory index. advanced: true adds the F3+H lines.

The rendered tooltip in a screenshot, or any behaviour that checks the key over time:

mc_key {key:"left_shift", action:"press"}     → held until released
mc_hover {slot: 36}                           → the mouse is over the slot, no click
mc_screenshot
mc_key {key:"left_shift", action:"release"}

The mc_key result lists heldKeys and what hasShiftDown(), hasControlDown() and hasAltDown() currently return. Keys stay held until you release them. Modifiers passed to mc_click, mc_click_widget and mc_key are held only for that one action.