diff --git a/piker/ui/_overlay.py b/piker/ui/_overlay.py
new file mode 100644
index 00000000..fd22e8e5
--- /dev/null
+++ b/piker/ui/_overlay.py
@@ -0,0 +1,272 @@
+# piker: trading gear for hackers
+# Copyright (C) Tyler Goodlet (in stewardship for pikers)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+'''
+Charting overlay helpers.
+
+'''
+from pyqtgraph.Qt.QtCore import (
+    # QObject,
+    # Signal,
+    Qt,
+    # QEvent,
+)
+from pyqtgraph.graphicsItems.AxisItem import AxisItem
+# from pyqtgraph.graphicsItems.ViewBox import ViewBox
+from pyqtgraph.graphicsItems.PlotItem.PlotItem import PlotItem
+from pyqtgraph.Qt.QtWidgets import QGraphicsGridLayout, QGraphicsLinearLayout
+
+# Define the layout "position" indices as to be passed
+# to a ``QtWidgets.QGraphicsGridlayout.addItem()`` call:
+# https://doc.qt.io/qt-5/qgraphicsgridlayout.html#addItem
+# This was pulled from the internals of ``PlotItem.setAxisItem()``.
+_axes_layout_indices: dict[str] = {
+    # row incremented axes
+    'top': (1, 1),
+    'bottom': (3, 1),
+
+    # view is @ (2, 1)
+
+    # column incremented axes
+    'left': (2, 0),
+    'right': (2, 2),
+}
+# NOTE: To clarify this indexing, ``PlotItem.__init__()`` makes a grid
+# with dimensions 4x3 and puts the ``ViewBox`` at postiion (2, 1) (aka
+# row=2, col=1) in the grid layout since row (0, 1) is reserved for
+# a title label and row 1 is for any potential "top" axis. Column 1
+# is the "middle" (since 3 columns) and is where the plot/vb is placed.
+
+
+class ComposedGridLayout:
+    '''
+    List-like interface to managing a sequence of overlayed
+    ``PlotItem``s in the form:
+
+    |    |     |    |    | top0     |    |    |     |    |
+    |    |     |    |    | top1     |    |    |     |    |
+    |    |     |    |    | ...      |    |    |     |    |
+    |    |     |    |    | topN     |    |    |     |    |
+    | lN | ... | l1 | l0 | ViewBox  | r0 | r1 | ... | rN |
+    |    |     |    |    | bottom0  |    |    |     |    |
+    |    |     |    |    | bottom1  |    |    |     |    |
+    |    |     |    |    | ...      |    |    |     |    |
+    |    |     |    |    | bottomN  |    |    |     |    |
+
+    Where the index ``i`` in the sequence specifies the index
+    ``<axis_name>i`` in the layout.
+
+    The ``item: PlotItem`` passed to the constructor's grid layout is
+    used verbatim as the "main plot" who's view box is give precedence
+    for input handling. The main plot's axes are removed from it's
+    layout and placed in the surrounding exterior layouts to allow for
+    re-ordering if desired.
+
+    '''
+    def __init__(
+        self,
+        item: PlotItem,
+        grid: QGraphicsGridLayout,
+        reverse: bool = False,  # insert items to the "center"
+
+    ) -> None:
+        self.items: list[PlotItem] = []
+        # self.grid = grid
+        self.reverse = reverse
+
+        # TODO: use a ``bidict`` here?
+        self._pi2axes: dict[
+            int,
+            dict[str, AxisItem],
+        ] = {}
+
+        self._axes2pi: dict[
+            AxisItem,
+            dict[str, PlotItem],
+        ] = {}
+
+        # TODO: better name?
+        # construct surrounding layouts for placing outer axes and
+        # their legends and title labels.
+        self.sides: dict[
+            str,
+            tuple[QGraphicsLinearLayout, list[AxisItem]]
+        ] = {}
+
+        for name, pos in _axes_layout_indices.items():
+            layout = QGraphicsLinearLayout()
+            self.sides[name] = (layout, [])
+
+            layout.setContentsMargins(0, 0, 0, 0)
+            layout.setSpacing(0)
+
+            if name in ('top', 'bottom'):
+                orient = Qt.Vertical
+            elif name in ('left', 'right'):
+                orient = Qt.Horizontal
+
+            layout.setOrientation(orient)
+
+        self.insert(0, item)
+
+        # insert surrounding linear layouts into the parent pi's layout
+        # such that additional axes can be appended arbitrarily without
+        # having to expand or resize the parent's grid layout.
+        for name, (linlayout, axes) in self.sides.items():
+
+            # TODO: do we need this?
+            # axis should have been removed during insert above
+            index = _axes_layout_indices[name]
+            axis = item.layout.itemAt(*index)
+            if axis and axis.isVisible():
+                assert linlayout.itemAt(0) is axis
+
+            # item.layout.removeItem(axis)
+            item.layout.addItem(linlayout, *index)
+            layout = item.layout.itemAt(*index)
+            assert layout is linlayout
+
+    def _register_item(
+        self,
+        index: int,
+        plotitem: PlotItem,
+
+    ) -> None:
+        for name, axis_info in plotitem.axes.items():
+            axis = axis_info['item']
+            # register this plot's (maybe re-placed) axes for lookup.
+            self._pi2axes.setdefault(index, {})[name] = axis
+            self._axes2pi.setdefault(index, {})[name] = plotitem
+
+        # enter plot into list for index tracking
+        self.items.insert(index, plotitem)
+
+    def insert(
+        self,
+        index: int,
+        plotitem: PlotItem,
+
+    ) -> (int, int):
+        '''
+        Place item at index by inserting all axes into the grid
+        at list-order appropriate position.
+
+        '''
+        if index < 0:
+            raise ValueError(f'`insert()` only supports an index >= 0')
+
+        # add plot's axes in sequence to the embedded linear layouts
+        # for each "side" thus avoiding graphics collisions.
+        for name, axis_info in plotitem.axes.copy().items():
+            linlayout, axes = self.sides[name]
+            axis = axis_info['item']
+
+            if axis in axes:
+                ValueError(f'{axis} is already in {name} layout!?')
+
+            # linking sanity
+            axis_view = axis.linkedView()
+            assert axis_view is plotitem.vb
+
+            if (
+                not axis.isVisible()
+
+                # XXX: we never skip moving the axes for the *first*
+                # plotitem inserted (even if not shown) since we need to
+                # move all the hidden axes into linear sub-layouts for
+                # that "central" plot in the overlay. Also if we don't
+                # do it there's weird geomoetry calc offsets that make
+                # view coords slightly off somehow .. smh
+                and not len(self.items) == 0
+            ):
+                continue
+
+            # XXX: Remove old axis? No, turns out we don't need this?
+            # DON'T unlink it since we the original ``ViewBox``
+            # to still drive it B)
+            # popped = plotitem.removeAxis(name, unlink=False)
+            # assert axis is popped
+
+            # invert insert index for layouts which are
+            # not-left-to-right, top-to-bottom insert oriented
+            if name in ('top', 'left'):
+                index = min(len(axes) - index, 0)
+                assert index >= 0
+
+            # elif name in ('bottom', 'right'):
+            #     i_dim = 1
+
+            # TODO: increment logic for layout on 'top'/'left' axes
+            # sets.. looks like ther'es no way around an unwind and
+            # re-stack of the layout to include all labels, unless
+            # we use a different layout system (cough).
+
+            # if name in ('top', 'left'):
+            #     increment = -1
+            # elif name in ('right', 'bottom'):
+            #     increment = +1
+
+            # increment = +count
+
+            # index = list(_axes_layout_indices[name])
+            # current = index[i_dim]
+            # index[i_dim] = current + increment if current > 0 else 0
+
+            linlayout.insertItem(index, axis)
+            # axis.setLayout(linlayout)
+            axes.insert(index, axis)
+
+        self._register_item(index, plotitem)
+
+        return index
+
+    def append(
+        self,
+        item: PlotItem,
+
+    ) -> (int, int):
+        '''
+        Append item's axes at indexes which put its axes "outside"
+        previously overlayed entries.
+
+        '''
+        # for left and bottom axes we have to first remove
+        # items and re-insert to maintain a list-order.
+        return self.insert(len(self.items), item)
+
+    def get_axis(
+        self,
+        plot: PlotItem,
+        name: str,
+
+    ) -> AxisItem:
+        '''
+        Retrieve the named axis for overlayed ``plot``.
+
+        '''
+        index = self.items.index(plot)
+        return self._pi2axes[index][name]
+
+    def pop(
+        self,
+        item: PlotItem,
+
+    ) -> PlotItem:
+        '''
+        Remove item and restack all axes in list-order.
+
+        '''
+        ...