--- a/src/Configuration.h	Sat Apr 10 21:10:17 2021 +0200
+++ b/src/Configuration.h	Sun Apr 11 14:37:11 2021 +0200
@@ -33,6 +33,8 @@
 	bool listWindows = false;
 	bool listScreens = false;
 
+	bool inheritProcessIdInWindowList = true;
+
 	virtual ~Configuration() {
 	}
 };

--- a/src/X11Command.h	Sat Apr 10 21:10:17 2021 +0200
+++ b/src/X11Command.h	Sun Apr 11 14:37:11 2021 +0200
@@ -323,7 +323,7 @@
 		return result;
 	}
 
-	void listWindow(const Display& display, Window window, relpipe::common::type::Integer level, Configuration& configuration, std::shared_ptr<writer::RelationalWriter> writer, std::function<void() > relationalWriterFlush) {
+	void listWindow(const Display& display, Window window, relpipe::common::type::Integer level, relpipe::common::type::Integer parentProcess, Configuration& configuration, std::shared_ptr<writer::RelationalWriter> writer, std::function<void() > relationalWriterFlush) {
 		Window rootWindow;
 		Window parentWindow;
 		unsigned int childrenCount;
@@ -347,6 +347,7 @@
 
 		// The PID as reported by the application itself in the property. Some applications do not report their PID.
 		relpipe::common::type::Integer processId = findWindowPropertyInteger(display, window, "_NET_WM_PID");
+		if (configuration.inheritProcessIdInWindowList && processId < 0) processId = parentProcess;
 		// TODO: support also other properties: customizable through options or all in a nested structure/relation/xml
 
 		writer->writeAttribute(std::to_wstring(window));
@@ -362,7 +363,7 @@
 		writer->writeAttribute(std::to_wstring(windowAttributes.width));
 		writer->writeAttribute(std::to_wstring(windowAttributes.height));
 
-		for (unsigned int i = 0; i < childrenCount; i++) listWindow(display, childrenList[i], level + 1, configuration, writer, relationalWriterFlush);
+		for (unsigned int i = 0; i < childrenCount; i++) listWindow(display, childrenList[i], level + 1, processId, configuration, writer, relationalWriterFlush);
 
 		XFree(childrenList);
 	}
@@ -385,7 +386,7 @@
 
 		for (int screenCount = XScreenCount(display.display), screen = 0; screen < screenCount; screen++) {
 			Window root = RootWindow(display.display, screen);
-			listWindow(display, root, 0, configuration, writer, relationalWriterFlush);
+			listWindow(display, root, 0, -1, configuration, writer, relationalWriterFlush);
 		}
 	}