implement Activity.isInMultiWindowMode()

src/api-impl-jni/app/android_app_Activity.c

@@ -311,3 +311,8 @@ JNIEXPORT void JNICALL Java_android_app_Activity_nativeFileChooser(JNIEnv *env,
 	gtk_native_dialog_show (GTK_NATIVE_DIALOG (native));
 #endif
 }
+
+JNIEXPORT jboolean JNICALL Java_android_app_Activity_isInMultiWindowMode(JNIEnv *env, jobject this)
+{
+	return !gtk_window_is_maximized(window);
+}

src/api-impl-jni/generated_headers/android_app_Activity.h

@@ -45,6 +45,14 @@ JNIEXPORT void JNICALL Java_android_app_Activity_nativeOpenURI
 JNIEXPORT void JNICALL Java_android_app_Activity_nativeFileChooser
   (JNIEnv *, jobject, jint, jstring, jstring, jint);
 
+/*
+ * Class:     android_app_Activity
+ * Method:    isInMultiWindowMode
+ * Signature: ()Z
+ */
+JNIEXPORT jboolean JNICALL Java_android_app_Activity_isInMultiWindowMode
+  (JNIEnv *, jobject);
+
 #ifdef __cplusplus
 }
 #endif

src/api-impl/android/app/Activity.java

@@ -575,5 +575,5 @@ public class Activity extends ContextThemeWrapper implements Window.Callback {
 	public Uri getReferrer() { return null; }
 	public void setDefaultKeyMode(int flag) {}
 	public void registerForContextMenu(View view) {}
-	public boolean isInMultiWindowMode() { return true; }
+	public native boolean isInMultiWindowMode();
 }