diff --git a/brainglobe_utils/qtpy/dialog.py b/brainglobe_utils/qtpy/dialog.py
index 69d24a0..9ba3cde 100644
--- a/brainglobe_utils/qtpy/dialog.py
+++ b/brainglobe_utils/qtpy/dialog.py
@@ -1,7 +1,7 @@
-from qtpy.QtWidgets import QMessageBox
+from qtpy.QtWidgets import QMessageBox, QWidget
 
 
-def display_warning(widget, title, message):
+def display_warning(widget: QWidget, title: str, message: str) -> bool:
     """
     Display a warning in a pop-up that can be accepted or dismissed
     """
diff --git a/brainglobe_utils/qtpy/interaction.py b/brainglobe_utils/qtpy/interaction.py
index 81369bc..a5ac1d8 100644
--- a/brainglobe_utils/qtpy/interaction.py
+++ b/brainglobe_utils/qtpy/interaction.py
@@ -1,24 +1,31 @@
+from typing import Callable, List, Optional, Tuple
+
 from qtpy.QtWidgets import (
     QCheckBox,
+    QComboBox,
     QDoubleSpinBox,
     QLabel,
+    QLayout,
     QPushButton,
     QSpinBox,
 )
 
 
 def add_button(
-    label,
-    layout,
-    connected_function,
+    label: str,
+    layout: QLayout,
+    connected_function: Callable,
     *,
     row: int = 0,
     column: int = 0,
-    visibility=True,
-    minimum_width=0,
-    alignment="center",
-    tooltip=None,
-):
+    visibility: bool = True,
+    minimum_width: int = 0,
+    alignment: str = "center",
+    tooltip: Optional[str] = None,
+) -> QPushButton:
+    """
+    Add a button to *layout*.
+    """
     button = QPushButton(label)
     if alignment == "center":
         pass
@@ -32,6 +39,7 @@ def add_button(
 
     if tooltip:
         button.setToolTip(tooltip)
+
     layout.addWidget(button, row, column)
     button.clicked.connect(connected_function)
     return button
@@ -92,3 +100,39 @@ def add_int_box(
     layout.addWidget(QLabel(label), row, column)
     layout.addWidget(box, row, column + 1)
     return box
+
+
+def add_combobox(
+    layout: QLayout,
+    label: str,
+    items: List[str],
+    row: int = 0,
+    column: int = 0,
+    label_stack: bool = False,
+    callback=None,
+    width: int = 150,
+) -> Tuple[QComboBox, Optional[QLabel]]:
+    """
+    Add a selection box to *layout*.
+    """
+    if label_stack:
+        combobox_row = row + 1
+        combobox_column = column
+    else:
+        combobox_row = row
+        combobox_column = column + 1
+    combobox = QComboBox()
+    combobox.addItems(items)
+    if callback:
+        combobox.currentIndexChanged.connect(callback)
+    combobox.setMaximumWidth = width
+
+    if label is not None:
+        combobox_label = QLabel(label)
+        combobox_label.setMaximumWidth = width
+        layout.addWidget(combobox_label, row, column)
+    else:
+        combobox_label = None
+
+    layout.addWidget(combobox, combobox_row, combobox_column)
+    return combobox, combobox_label
diff --git a/tests/tests/test_qtpy/test_interaction.py b/tests/tests/test_qtpy/test_interaction.py
new file mode 100644
index 0000000..68fd1f3
--- /dev/null
+++ b/tests/tests/test_qtpy/test_interaction.py
@@ -0,0 +1,39 @@
+import pytest
+from qtpy.QtWidgets import QGridLayout
+
+from brainglobe_utils.qtpy.interaction import add_button, add_combobox
+
+
+@pytest.mark.parametrize("label_stack", [True, False])
+@pytest.mark.parametrize("label", ["A label", None])
+def test_add_combobox(label, label_stack):
+    """
+    Smoke test for add_combobox for all conditional branches
+    """
+    layout = QGridLayout()
+    combobox = add_combobox(
+        layout,
+        row=0,
+        label=label,
+        items=["item 1", "item 2"],
+        label_stack=label_stack,
+    )
+    assert combobox is not None
+
+
+@pytest.mark.parametrize(
+    argnames="alignment", argvalues=["center", "left", "right"]
+)
+def test_add_button(alignment):
+    """
+    Smoke tests for add_button for all conditional branches
+    """
+    layout = QGridLayout()
+    button = add_button(
+        layout=layout,
+        connected_function=lambda: None,
+        label="A button",
+        row=0,
+        alignment=alignment,
+    )
+    assert button is not None