Exempt ReaSampler 9000's own editor from the plugin OS drag hand-off

A dragged bank card over our own instrument's editor was OLE-dropping like a third-party plugin. Classify our channel's own .vst3 module as Instrument, not Plugin, so it keeps the normal instrument-drop outcome.

tests/test_window_origin.cpp

@@ -23,6 +23,14 @@ static WindowFacts inModule(const std::string& path, bool host = false) {
     return f;
 }
 
+static WindowFacts ownModule(const std::string& path) {
+    WindowFacts f;
+    f.procResolved = true;
+    f.modulePath = path;
+    f.ownModule = true;
+    return f;
+}
+
 // --- classifyWindowCode --------------------------------------------------------
 
 // REAPER's own chrome and containers: the class procedure lives in the executable.
@@ -103,6 +111,17 @@ static void testMissingSystemRootNeverYieldsPlugin() {
     CHECK(classifyWindowCode(inModule("C:\\REAPER\\reaper.exe", true), "") == WindowCode::Host);
 }
 
+// Our own ReaSampler 9000 module — stable or beta, whichever the shell set ownModule for — is
+// Instrument, not Plugin: FX chrome we own, so a drag over it must not hand off to the OS.
+static void testOwnModuleIsInstrument() {
+    CHECK(classifyWindowCode(
+              ownModule("C:\\Program Files\\Common Files\\VST3\\reasampler_9000.vst3"), kWinDir) ==
+          WindowCode::Instrument);
+    CHECK(classifyWindowCode(
+              ownModule("C:\\Program Files\\Common Files\\VST3\\reasampler_9000_beta.vst3"),
+              kWinDir) == WindowCode::Instrument);
+}
+
 // --- isPluginEditorChain -------------------------------------------------------
 
 // Pointer on REAPER's FX-window chrome: a standard control or a REAPER container, under the
@@ -134,6 +153,19 @@ static void testBridgedEmbeddedEditorIsPlugin() {
                                WindowCode::System}));
 }
 
+// A pointer over our own instrument's editor — Instrument code, not Plugin — is not hand-off
+// proof: it stays REAPER's FX chrome, unlike a genuine plugin editor (testPluginWindowChainIsPlugin).
+static void testOwnInstrumentChainIsNotPlugin() {
+    CHECK(!isPluginEditorChain({WindowCode::Instrument, WindowCode::Host, WindowCode::System}));
+}
+
+// Another plugin's editor sitting alongside our own instrument in the same chain is still proof —
+// only OUR module is exempted, nobody else's.
+static void testOtherPluginBesideOwnInstrumentIsStillPlugin() {
+    CHECK(isPluginEditorChain(
+        {WindowCode::Plugin, WindowCode::Instrument, WindowCode::Host, WindowCode::System}));
+}
+
 // Unknown anywhere, and nothing else, is not proof; an empty chain (no window at all) is not.
 static void testUnknownAndEmptyChainsAreNotPlugin() {
     CHECK(!isPluginEditorChain({WindowCode::Unknown, WindowCode::Host, WindowCode::System}));
@@ -150,11 +182,14 @@ int main() {
     testOtherProcessIsPluginRegardlessOfModule();
     testUnresolvedProcIsUnknown();
     testMissingSystemRootNeverYieldsPlugin();
+    testOwnModuleIsInstrument();
 
     testChromeChainIsNotPlugin();
     testPluginWindowChainIsPlugin();
     testStandardControlInsidePluginIsPlugin();
     testBridgedEmbeddedEditorIsPlugin();
+    testOwnInstrumentChainIsNotPlugin();
+    testOtherPluginBesideOwnInstrumentIsStillPlugin();
     testUnknownAndEmptyChainsAreNotPlugin();
 
     if (g_fail == 0) std::printf("All tests passed.\n");