Everything is working.

src/modules/fancyzones/dll/dllmain.cpp

@@ -1,5 +1,6 @@
 #include "pch.h"
 #include <common/settings_objects.h>
+#include <common/dpi_aware.h>
 #include <interface/powertoy_module_interface.h>
 #include <interface/lowlevel_keyboard_event_data.h>
 #include <interface/win_hook_event_data.h>
@@ -27,29 +28,18 @@ BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReser
     return TRUE;
 }
 
-// TODO: multimon support, need to pass the HMONITOR from the editor to here instead
-// of using MonitorFromPoint
 // This function is exported and called from FancyZonesEditor.exe to save a layout from the editor.
 STDAPI PersistZoneSet(
     PCWSTR activeKey, // Registry key holding ActiveZoneSet
+    PCWSTR resolutionKey, // Registry key to persist ZoneSet to
     HMONITOR monitor,
     WORD layoutId, // LayoutModel Id
     int zoneCount, // Number of zones in zones
     int zones[]) // Array of zones serialized in left/top/right/bottom chunks
 {
     // See if we have already persisted this layout we can update.
-    std::wstringstream stream;
-    MONITORINFOEX mi;
-    mi.cbSize = sizeof(mi);
-    if (GetMonitorInfo(monitor, &mi))
-    {
-        stream << (mi.rcMonitor.right - mi.rcMonitor.left) << "_";
-        stream << (mi.rcMonitor.bottom - mi.rcMonitor.top);
-    }
-
-    std::wstring resolutionKey(stream.str());
     UUID id{GUID_NULL};
-    if (wil::unique_hkey key{ RegistryHelpers::OpenKey(resolutionKey.c_str()) })
+    if (wil::unique_hkey key{ RegistryHelpers::OpenKey(resolutionKey) })
     {
         ZoneSetPersistedData data{};
         DWORD dataSize = sizeof(data);
@@ -84,7 +74,7 @@ STDAPI PersistZoneSet(
                 id,
                 layoutId,
                 reinterpret_cast<HMONITOR>(monitor),
-                resolutionKey.c_str(),
+                resolutionKey,
                 ZoneSetLayout::Custom,
                 0, 0, 0));
 

src/modules/fancyzones/editor/FancyZonesEditor/Models/LayoutModel.cs

@@ -155,6 +155,7 @@ internal static class Native
 
             internal delegate int PersistZoneSet(
                 [MarshalAs(UnmanagedType.LPWStr)] string activeKey,
+                [MarshalAs(UnmanagedType.LPWStr)] string resolutionKey,
                 uint monitor,
                 ushort layoutId,
                 int zoneCount,
@@ -201,7 +202,7 @@ public void Apply(System.Windows.Int32Rect[] zones)
             }
 
             var persistZoneSet = Marshal.GetDelegateForFunctionPointer<Native.PersistZoneSet>(pfn);
-            persistZoneSet(Settings.UniqueKey, Settings.Monitor, _id, zoneCount, zoneArray);
+            persistZoneSet(Settings.UniqueKey, Settings.WorkAreaKey, Settings.Monitor, _id, zoneCount, zoneArray);
         }
 
         private static readonly string c_registryPath = Settings.RegistryPath + "\\Layouts";

src/modules/fancyzones/editor/FancyZonesEditor/Models/Settings.cs

@@ -153,6 +153,12 @@ public static String UniqueKey
         private static String _uniqueKey;
         private String _uniqueRegistryPath;
 
+        public static String WorkAreaKey
+        {
+            get { return _workAreaKey; }
+        }
+        private static String _workAreaKey;
+
         public static float Dpi
         {
             get { return _dpi; }
@@ -267,26 +273,27 @@ private void ParseCommandLineArgs()
             _dpi = 1;
 
             string[] args = Environment.GetCommandLineArgs();
-            if (args.Length == 6)
+            if (args.Length == 7)
             {
                 // 1 = unique key for per-monitor settings
-                // 2 = layoutid used to generate current layout
-                // 3 = handle to foreground window (used to figure out which monitor to show on)
-                // 4 = handle to monitor (passed back to engine to persist data)
-                // 5 = monitor DPI (float)
+                // 2 = layoutid used to generate current layout (used to pick the default layout to show)
+                // 3 = handle to monitor (passed back to engine to persist data)
+                // 4 = X_Y_Width_Height (where EditorOverlay shows up)
+                // 5 = resolution key (passed back to engine to persist data)
+                // 6 = monitor DPI (float)
 
                 _uniqueKey = args[1];
                 _uniqueRegistryPath += "\\" + _uniqueKey;
 
-                var foregroundWindow = new IntPtr(uint.Parse(args[3]));
-                var screen = System.Windows.Forms.Screen.FromHandle(foregroundWindow);
+                var parsedLocation = args[4].Split('_');
+                var x = int.Parse(parsedLocation[0]);
+                var y = int.Parse(parsedLocation[1]);
+                var width = int.Parse(parsedLocation[2]);
+                var height = int.Parse(parsedLocation[3]);
 
-                _dpi = float.Parse(args[5]);
-                _workArea = new Rect(
-                    screen.WorkingArea.X / _dpi,
-                    screen.WorkingArea.Y / _dpi,
-                    screen.WorkingArea.Width / _dpi,
-                    screen.WorkingArea.Height / _dpi);
+                _workAreaKey = args[5];
+                _dpi = float.Parse(args[6]);
+                _workArea = new Rect(x, y, width, height);
 
                 uint monitor = 0;
                 if (uint.TryParse(args[4], out monitor))

src/modules/fancyzones/lib/FancyZones.cpp

@@ -249,11 +249,23 @@ void FancyZones::ToggleEditor() noexcept
             UINT dpi_y = 96;
             DPIAware::GetScreenDPIForWindow(foregroundWindow, dpi_x, dpi_y);
 
+            MONITORINFOEX mi;
+            mi.cbSize = sizeof(mi);
+            GetMonitorInfo(monitor, &mi);
+
+            // Location that the editor should occupy, scaled by DPI
+            std::wstring editorLocation = 
+                std::to_wstring(MulDiv(mi.rcWork.left, 96, dpi_x)) + L"_" +
+                std::to_wstring(MulDiv(mi.rcWork.top, 96, dpi_y)) + L"_" +
+                std::to_wstring(MulDiv(mi.rcWork.right - mi.rcWork.left, 96, dpi_x)) + L"_" +
+                std::to_wstring(MulDiv(mi.rcWork.bottom - mi.rcWork.top, 96, dpi_y));
+
             const std::wstring params =
                 iter->second->UniqueId() + L" " +
                 std::to_wstring(iter->second->ActiveZoneSet()->LayoutId()) + L" " +
-                std::to_wstring(reinterpret_cast<UINT_PTR>(foregroundWindow)) + L" " +
                 std::to_wstring(reinterpret_cast<UINT_PTR>(monitor)) + L" " +
+                editorLocation + L" " +
+                iter->second->WorkAreaKey() + L" " +
                 std::to_wstring(static_cast<float>(dpi_x) / 96.0f);
 
             SHELLEXECUTEINFO sei{ sizeof(sei) };

src/modules/fancyzones/lib/ZoneWindow.cpp

@@ -18,6 +18,7 @@ struct ZoneWindow : public winrt::implements<ZoneWindow, IZoneWindow>
     IFACEMETHODIMP_(void) CycleActiveZoneSet(DWORD vkCode) noexcept;
     IFACEMETHODIMP_(std::wstring) DeviceId() noexcept { return { m_deviceId.get() }; }
     IFACEMETHODIMP_(std::wstring) UniqueId() noexcept { return { m_uniqueId }; }
+    IFACEMETHODIMP_(std::wstring) WorkAreaKey() noexcept { return { m_workArea }; }
     IFACEMETHODIMP_(void) SaveWindowProcessToZoneIndex(HWND window) noexcept;
     IFACEMETHODIMP_(IZoneSet*) ActiveZoneSet() noexcept { return m_activeZoneSet.get(); }
 

src/modules/fancyzones/lib/ZoneWindow.h

@@ -16,6 +16,7 @@ interface __declspec(uuid("{7F017528-8110-4FB3-BE41-F472969C2560}")) IZoneWindow
     IFACEMETHOD_(void, SaveWindowProcessToZoneIndex)(HWND window) = 0;
     IFACEMETHOD_(std::wstring, DeviceId)() = 0;
     IFACEMETHOD_(std::wstring, UniqueId)() = 0;
+    IFACEMETHOD_(std::wstring, WorkAreaKey)() = 0;
     IFACEMETHOD_(IZoneSet*, ActiveZoneSet)() = 0;
 };