Provide current thoughts on Qt and the keyboard.

OSBindings/Qt/mainwindow.cpp

@@ -768,10 +768,40 @@ void MainWindow::keyReleaseEvent(QKeyEvent *event) {
 bool MainWindow::processEvent(QKeyEvent *event) {
 	if(!machine) return true;
 
-	// First version: support keyboard input only.
 	const auto keyboardMachine = machine->keyboard_machine();
 	if(!keyboardMachine) return true;
 
+	// Qt is the worst.
+	//
+	// Assume your keyboard has a key labelled both . and >, as they do on US and UK keyboards. Call it the dot key.
+	// Perform the following:
+	//	1.	press dot key;
+	//	2.	press shift key;
+	//	3.	release dot key;
+	//	4.	release shift key.
+	//
+	// Per empirical testing, and key repeat aside, on both macOS and Ubuntu 19.04 that sequence will result in
+	// _three_ keypress events, but only _two_ key release events. You'll get presses for Qt::Key_Period, Qt::Key_Greater
+	// and Qt::Key_Shift. You'll get releases only for Qt::Key_Greater and Qt::Key_Shift.
+	//
+	// How can you detect at runtime that Key_Greater and Key_Period are the same physical key?
+	//
+	// You can't. On Ubuntu they have the same values for QKeyEvent::nativeScanCode(), which are unique to the key,
+	// but they have different ::nativeVirtualKey()s.
+	//
+	// On macOS they have the same ::nativeScanCode() only because on macOS [almost] all keys have the same
+	// ::nativeScanCode(). So that's not usable. They have the same ::nativeVirtualKey()s, but since that isn't true
+	// on Ubuntu, that's also not usable.
+	//
+	// So how can you track the physical keys on a keyboard via Qt?
+	//
+	// You can't. Qt is the worst. SDL doesn't have this problem, including in X11, so this seems to be a problem
+	// Qt has invented for itself.
+	//
+	// TODO: find a workaround. Platform-specific use of either nativeScanCode() or nativeVirtualKey() maybe,
+	// but if so, how to interpret the meaning?
+
+
 #define BIND2(qtKey, clkKey) case Qt::qtKey: key = Inputs::Keyboard::Key::clkKey; break;
 #define BIND(key) BIND2(Key_##key, key)
 
@@ -779,10 +809,6 @@ bool MainWindow::processEvent(QKeyEvent *event) {
 	switch(event->key()) {
 		default: return true;
 
-		// TODO: Qt factors in modifiers when deciding which key to declare has been pressed.
-		// E.g. on my keyboard a shifted Key_Comma produces a Key_Less, not a Key_Comma and a shift.
-		// Find a way to disable that, or else work around it here.
-
 		BIND(Escape);
 		BIND(F1);	BIND(F2);	BIND(F3);	BIND(F4);	BIND(F5);	BIND(F6);
 		BIND(F7);	BIND(F8);	BIND(F9);	BIND(F10);	BIND(F11);	BIND(F12);

README.md

@@ -4,7 +4,7 @@ Clock Signal ('CLK') is an emulator for tourists that seeks to be invisible. Use
 
 [Releases](https://github.com/TomHarte/CLK/releases) are hosted on GitHub.
 
-On the Mac it is a native Cocoa application; under Linux, BSD and other UNIXes and UNIX-alikes it can be built either with Qt or with SDL.
+On the Mac it is a native Cocoa application; under Linux, BSD and other UNIXes and UNIX-alikes it can be built either with Qt or with SDL; the Qt build should be considered preliminary, pending a sustainable workaround for its keyboard handling.
 
 So its aims are:
 * single-click load of any piece of source media for any supported platform;