Clean up stale editor-hInstance comments, add isOwnModulePath edge tests

Drops a false claim about ReaSampler's own editor's hInstance, corrects the real reason for registering the wndproc class against our own module, and covers isOwnModulePath's separator edge cases.

src/shell/actions/drag_out_win.cpp

@@ -378,8 +378,8 @@ ui::WindowFacts windowFacts(HWND hwnd) {
 
 bool pointerOverPluginEditor(int screenX, int screenY) {
     // The CLASS procedure's module rather than the window's hInstance: a bare-SDK plugin may
-    // create its editor with the hInstance of the parent REAPER hands it (ReaSampler 9000's own
+    // create its editor with the hInstance of the parent REAPER hands it, so hInstance would
-    // editor does), so hInstance would read that plugin as REAPER.
+    // read that plugin as REAPER.
     const POINT pt{screenX, screenY};
     const HWND hit = WindowFromPoint(pt);
     if (!hit) return false;

src/shell/instrument/editor_platform.cpp

@@ -36,10 +36,10 @@ const std::wstring& childClassName() {
 
 // The module holding a given code address — used to resolve THIS wndProc's own module rather
 // than the parent's hInstance REAPER hands us. Registering against the parent would put the class
-// in REAPER's own module, where a second .vst3 (the other channel) sharing that hInstance could
+// in REAPER's own module while the wndproc still points into our DLL — a dangling procedure
-// collide on the (now channel-forked) name, and any lookup-by-class would resolve into the wrong
+// pointer once our DLL unloads but REAPER's class registration outlives it. Takes the address
-// binary. Takes the address rather than naming wndProc directly so a free function in this
+// rather than naming wndProc directly so a free function in this anonymous namespace doesn't need
-// anonymous namespace doesn't need access to the private member.
+// access to the private member.
 HMODULE moduleHandleFor(void* codeAddress) {
     HMODULE mod = nullptr;
     GetModuleHandleExW(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |

tests/test_window_origin.cpp

@@ -194,6 +194,18 @@ static void testOwnModulePathStableAndBetaDoNotMatchEachOther() {
     CHECK(!isOwnModulePath("C:\\VST3\\reasampler_9000.vst3", "reasampler_9000_beta.vst3"));
 }
 
+static void testOwnModulePathBareFilenameWithNoSeparatorMatches() {
+    CHECK(isOwnModulePath("reasampler_9000.vst3", "reasampler_9000.vst3"));
+}
+
+static void testOwnModulePathEmptyPathDoesNotMatch() {
+    CHECK(!isOwnModulePath("", "reasampler_9000.vst3"));
+}
+
+static void testOwnModulePathTrailingSeparatorDoesNotMatch() {
+    CHECK(!isOwnModulePath("C:\\VST3\\reasampler_9000.vst3\\", "reasampler_9000.vst3"));
+}
+
 int main() {
     testHostExecutableIsHost();
     testOsModulesAreSystem();
@@ -216,6 +228,9 @@ int main() {
     testOwnModulePathCaseFolds();
     testOwnModulePathBundlePathForwardAndBackSlash();
     testOwnModulePathStableAndBetaDoNotMatchEachOther();
+    testOwnModulePathBareFilenameWithNoSeparatorMatches();
+    testOwnModulePathEmptyPathDoesNotMatch();
+    testOwnModulePathTrailingSeparatorDoesNotMatch();
 
     if (g_fail == 0) std::printf("All tests passed.\n");
     return g_fail ? 1 : 0;