diff --git a/.github/workflows/python-package.yml b/.github/workflows/python-package.yml
index 7b4cb0ac..375a70fb 100644
--- a/.github/workflows/python-package.yml
+++ b/.github/workflows/python-package.yml
@@ -72,7 +72,7 @@ jobs:
 
       - run: |
           mk python-release owner=vkottler \
-                            repo=runtimepy version=4.5.0
+                            repo=runtimepy version=4.5.1
         if: |
           matrix.python-version == '3.11'
           && matrix.system == 'ubuntu-latest'
diff --git a/README.md b/README.md
index 421fe625..31d54fa1 100644
--- a/README.md
+++ b/README.md
@@ -2,11 +2,11 @@
     =====================================
     generator=datazen
     version=3.1.4
-    hash=48a3836c8cab67b925fe019f3db34c8d
+    hash=c9e8e0a4b1765408663652c02a32e75e
     =====================================
 -->
 
-# runtimepy ([4.5.0](https://pypi.org/project/runtimepy/))
+# runtimepy ([4.5.1](https://pypi.org/project/runtimepy/))
 
 [![python](https://img.shields.io/pypi/pyversions/runtimepy.svg)](https://pypi.org/project/runtimepy/)
 ![Build Status](https://github.com/vkottler/runtimepy/workflows/Python%20Package/badge.svg)
diff --git a/local/variables/package.yaml b/local/variables/package.yaml
index 175b2006..715f03b9 100644
--- a/local/variables/package.yaml
+++ b/local/variables/package.yaml
@@ -1,5 +1,5 @@
 ---
 major: 4
 minor: 5
-patch: 0
+patch: 1
 entry: runtimepy
diff --git a/pyproject.toml b/pyproject.toml
index 276af13c..58896b7b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta:__legacy__"
 
 [project]
 name = "runtimepy"
-version = "4.5.0"
+version = "4.5.1"
 description = "A framework for implementing Python services."
 readme = "README.md"
 requires-python = ">=3.11"
diff --git a/runtimepy/__init__.py b/runtimepy/__init__.py
index b8e99d1f..bd426d42 100644
--- a/runtimepy/__init__.py
+++ b/runtimepy/__init__.py
@@ -1,7 +1,7 @@
 # =====================================
 # generator=datazen
 # version=3.1.4
-# hash=9539398893e7a420adf97d118b6bcabf
+# hash=4c10d97db8d952d1b242acfcfd80abb4
 # =====================================
 
 """
@@ -10,7 +10,7 @@
 
 DESCRIPTION = "A framework for implementing Python services."
 PKG_NAME = "runtimepy"
-VERSION = "4.5.0"
+VERSION = "4.5.1"
 
 # runtimepy-specific content.
 METRICS_NAME = "metrics"
diff --git a/runtimepy/channel/environment/base.py b/runtimepy/channel/environment/base.py
index a92b1102..2ac6f5b5 100644
--- a/runtimepy/channel/environment/base.py
+++ b/runtimepy/channel/environment/base.py
@@ -106,13 +106,15 @@ def __setitem__(self, key: _RegistryKey, value: ChannelValue) -> None:
         """Mapping-set interface."""
         return self.set(key, value)
 
-    def set(self, key: _RegistryKey, value: ChannelValue) -> None:
+    def set(
+        self, key: _RegistryKey, value: ChannelValue, scaled: bool = True
+    ) -> None:
         """Attempt to set an arbitrary channel value."""
 
         # Set a field value if this key maps to a bit-field.
         if self.fields.has_field(key):
             assert not isinstance(value, float)
-            self.fields.set(key, value)
+            self.fields.set(key, value, scaled=scaled)
             return
 
         chan, enum = self[key]
@@ -155,7 +157,10 @@ def set(self, key: _RegistryKey, value: ChannelValue) -> None:
                 )
 
         # Assign the value to the channel.
-        chan.raw.scaled = value  # type: ignore
+        if scaled:
+            chan.raw.scaled = value  # type: ignore
+        else:
+            chan.raw.value = value  # type: ignore
 
     def apply(self, values: ValueMap) -> None:
         """Apply a map of values to the environment."""
@@ -172,17 +177,19 @@ def values(self, resolve_enum: bool = True) -> ValueMap:
         }
 
     def value(
-        self, key: _RegistryKey, resolve_enum: bool = True
+        self, key: _RegistryKey, resolve_enum: bool = True, scaled: bool = True
     ) -> ChannelValue:
         """Attempt to get a channel's current value."""
 
         # Get the value from a field if this key points to a bit-field.
         if self.fields.has_field(key):
-            return self.fields.get(key, resolve_enum=resolve_enum)
+            return self.fields.get(
+                key, resolve_enum=resolve_enum, scaled=scaled
+            )
 
         chan, enum = self[key]
 
-        value: ChannelValue = chan.raw.scaled
+        value: ChannelValue = chan.raw.scaled if scaled else chan.raw.value
 
         # Resolve enumeration values to strings.
         if enum is not None and resolve_enum:
diff --git a/runtimepy/data/js/classes/Plot.js b/runtimepy/data/js/classes/Plot.js
index 243b54a6..81f326c5 100644
--- a/runtimepy/data/js/classes/Plot.js
+++ b/runtimepy/data/js/classes/Plot.js
@@ -17,9 +17,12 @@ class Plot {
     let plotButton = document.getElementById("runtimepy-plot-button");
     if (plotButton) {
       this.canvas.onclick = (event) => { plotButton.click(); };
+      this.canvas.onwheel = this.onWheel.bind(this);
     }
   }
 
+  onWheel(event) { this.plotMessage({"wheelDelta" : event.wheelDelta}); }
+
   plotMessage(data, param) { this.worker.toWorker({"plot" : data}, param); }
 
   messageBase() {
diff --git a/runtimepy/data/js/classes/PlotDrawer.js b/runtimepy/data/js/classes/PlotDrawer.js
index 45049c0d..657d034e 100644
--- a/runtimepy/data/js/classes/PlotDrawer.js
+++ b/runtimepy/data/js/classes/PlotDrawer.js
@@ -109,4 +109,15 @@ class PlotDrawer {
 
     this.wglp.viewport(0, 0, this.canvas.width, this.canvas.height);
   }
+
+  updateDepth(wheelDelta) {
+    for (let name in this.channels) {
+      let chan = this.channels[name];
+
+      /* Make configurable at some point? */
+      chan.buffer.bumpCapacity(wheelDelta > 0);
+
+      chan.draw(this.lines[name]);
+    }
+  }
 }
diff --git a/runtimepy/data/js/classes/PlotManager.js b/runtimepy/data/js/classes/PlotManager.js
index 0b87e8f9..1dfe5e73 100644
--- a/runtimepy/data/js/classes/PlotManager.js
+++ b/runtimepy/data/js/classes/PlotManager.js
@@ -48,6 +48,12 @@ class PlotManager {
     }
   }
 
+  updateDepth(name, wheelDelta) {
+    if (name in this.drawers) {
+      this.drawers[name].updateDepth(wheelDelta);
+    }
+  }
+
   async handleMessage(data) {
     let name = data["name"];
 
@@ -56,6 +62,11 @@ class PlotManager {
       this.plots[name] = data["canvas"];
     }
 
+    /* Handle scroll events. */
+    if ("wheelDelta" in data) {
+      this.updateDepth(name, data["wheelDelta"]);
+    }
+
     /* Handle size updates. */
     if ("width" in data && "height" in data) {
       let canvas = this.plots[name];
diff --git a/runtimepy/data/js/classes/PointBuffer.js b/runtimepy/data/js/classes/PointBuffer.js
index 45acff14..e8dfe9dd 100644
--- a/runtimepy/data/js/classes/PointBuffer.js
+++ b/runtimepy/data/js/classes/PointBuffer.js
@@ -4,9 +4,20 @@ class PointBuffer {
     this.values = [];
     this.timestamps = [];
 
+    this.elements = 0;
     this.updateCapacity(capacity);
   }
 
+  bumpCapacity(bumpUp) {
+    /*
+     * need persistent settings for scroll behavior? (configurable?)
+     */
+    let scale_factor = 1.25;
+    let newCapacity = Math.max(16, bumpUp ? this.capacity * scale_factor
+                                          : this.capacity / scale_factor);
+    this.updateCapacity(Math.round(newCapacity));
+  }
+
   reset() {
     this.head = 0;
     this.tail = 0;
@@ -16,20 +27,32 @@ class PointBuffer {
   }
 
   updateCapacity(capacity) {
-    this.capacity = capacity;
-    this.reset();
+    /* Copy existing values. */
+    let points = [];
 
-    let newValues = new Array(this.capacity);
-    let newTimestamps = new Array(this.capacity);
+    let count = Math.min(this.elements, capacity, this.capacity);
+    if (count > 0) {
+      let startIdx = this.head;
 
-    /* Copy existing values. */
-    for (let i = this.values.length; i < this.capacity; i++) {
-      newValues[i] = this.values[i];
-      newTimestamps[i] = this.timestamps[i];
+      /* If the buffer is getting smaller, advance the buffer index forward. */
+      if (count < this.elements) {
+        startIdx += this.elements - count;
+        startIdx = startIdx % this.capacity;
+      }
+
+      for (let i = 0; i < count - 1; i++) {
+        let idx = (startIdx + i) % this.capacity;
+        points.push([ this.values[idx], this.timestamps[idx] ]);
+      }
     }
 
-    this.values = newValues;
-    this.timestamps = newTimestamps;
+    /* Reset state and re-ingest points. */
+    this.reset();
+    this.capacity = capacity;
+    this.values = new Array(this.capacity);
+    this.timestamps = new Array(this.capacity);
+
+    this.ingest(points);
   }
 
   ingest(points) {
@@ -62,15 +85,29 @@ class PointBuffer {
      */
 
     let slope = 2 / (newestTimestamp - oldestTimestamp);
-
-    /* Build array of plot-able timestamp X values. */
     let times = [];
-    let idx = oldestIdx;
-    while (idx != newestIdx) {
+
+    if (slope > 0) {
+      /* Build array of plot-able timestamp X values. */
+      let idx = oldestIdx;
+
+      while (idx != newestIdx) {
+        times.push(((this.timestamps[idx] - oldestTimestamp) * slope) - 1);
+        idx = this.incrIndex(idx);
+      }
       times.push(((this.timestamps[idx] - oldestTimestamp) * slope) - 1);
-      idx = this.incrIndex(idx);
+
+    } else {
+      /* need to root-cause this off-by-one issue */
+      console.log(`${newestIdx}, ${oldestIdx}, ${this.elements}`);
+      console.log(slope);
+
+      let idx = oldestIdx;
+      while (idx != newestIdx) {
+        times.push(oldestTimestamp)
+        idx = this.incrIndex(idx);
+      }
     }
-    times.push(((this.timestamps[idx] - oldestTimestamp) * slope) - 1);
 
     return times;
   }
diff --git a/runtimepy/primitives/base.py b/runtimepy/primitives/base.py
index a771a104..f7173714 100644
--- a/runtimepy/primitives/base.py
+++ b/runtimepy/primitives/base.py
@@ -3,11 +3,13 @@
 """
 
 # built-in
+from contextlib import contextmanager as _contextmanager
 from copy import copy as _copy
 from math import isclose as _isclose
 from typing import BinaryIO as _BinaryIO
 from typing import Callable as _Callable
 from typing import Generic as _Generic
+from typing import Iterator as _Iterator
 from typing import TypeVar as _TypeVar
 
 # third-party
@@ -104,6 +106,18 @@ def remove_callback(self, callback_id: int) -> bool:
             del self.callbacks[callback_id]
         return result
 
+    @_contextmanager
+    def callback(
+        self, callback: PrimitiveChangeCallaback[T]
+    ) -> _Iterator[None]:
+        """Register a callback as a managed context."""
+
+        ident = self.register_callback(callback)
+        try:
+            yield
+        finally:
+            self.remove_callback(ident)
+
     @property
     def value(self) -> T:
         """Obtain the underlying value."""
diff --git a/runtimepy/primitives/field/manager/base.py b/runtimepy/primitives/field/manager/base.py
index 79b784fb..a75e52e6 100644
--- a/runtimepy/primitives/field/manager/base.py
+++ b/runtimepy/primitives/field/manager/base.py
@@ -108,9 +108,17 @@ def add(self, fields: _BitFields) -> int:
 
         return index
 
-    def set(self, key: _RegistryKey, value: _Union[int, bool, str]) -> None:
+    def set(
+        self,
+        key: _RegistryKey,
+        value: _Union[int, bool, str],
+        scaled: bool = True,
+    ) -> None:
         """Set a value of a field."""
 
+        # Bit fields don't support scaling.
+        del scaled
+
         field = self[key]
 
         if isinstance(value, str):
@@ -125,10 +133,13 @@ def set(self, key: _RegistryKey, value: _Union[int, bool, str]) -> None:
         field(int(value))
 
     def get(
-        self, key: _RegistryKey, resolve_enum: bool = True
+        self, key: _RegistryKey, resolve_enum: bool = True, scaled: bool = True
     ) -> _Union[int, bool, str]:
         """Get the value of a field."""
 
+        # Bit fields don't support scaling.
+        del scaled
+
         field = self[key]
         value: _Union[int, str] = field()
 
diff --git a/tests/channel/environment/test_environment.py b/tests/channel/environment/test_environment.py
index 5838d822..4bd78aeb 100644
--- a/tests/channel/environment/test_environment.py
+++ b/tests/channel/environment/test_environment.py
@@ -173,3 +173,5 @@ def test_channel_environment_basic():
     assert env.get_int(4) is not None
 
     verify_missing_keys(env)
+
+    env.set("float.1", 1.0, scaled=False)
diff --git a/tests/data/valid/connection_arbiter/runtimepy_http.yaml b/tests/data/valid/connection_arbiter/runtimepy_http.yaml
index 7b7006f5..6a98840a 100644
--- a/tests/data/valid/connection_arbiter/runtimepy_http.yaml
+++ b/tests/data/valid/connection_arbiter/runtimepy_http.yaml
@@ -8,6 +8,7 @@ app:
 config:
   experimental: true
   foo: bar
+  xdg_fragment: "wave1,hide-tabs,hide-channels/wave1:sin,cos"
 
 clients:
   - factory: runtimepy_http
diff --git a/tests/primitives/test_bool.py b/tests/primitives/test_bool.py
index 34180d3f..de1be5d7 100644
--- a/tests/primitives/test_bool.py
+++ b/tests/primitives/test_bool.py
@@ -17,3 +17,19 @@ def test_bool_basic():
 
     prim.clear()
     assert copied()
+
+    call_count = 0
+
+    def change_cb(_: bool, __: bool) -> None:
+        """A sample callback."""
+        nonlocal call_count
+        call_count += 1
+
+    with prim.callback(change_cb):
+        prim.toggle()
+        prim.toggle()
+
+    prim.toggle()
+    prim.toggle()
+
+    assert call_count == 2