An ugly fix for numpad, since it seems event.key.keysym.mod isn't ent…

…irely reliable for some unknown reason

Partial revert of 7ce9907

src/PowderToySDL.cpp

@@ -450,15 +450,20 @@ float currentWidth, currentHeight;
 void EventProcess(SDL_Event event)
 {
 	if (event.type == SDL_KEYDOWN || event.type == SDL_KEYUP)
-		if ((!(event.key.keysym.mod&KEY_MOD_NUM)) ^ (!!(event.key.keysym.mod&KEY_MOD_SHIFT)))
+	{
+		if (event.key.keysym.unicode==0)
 		{
+			// If unicode is zero, this could be a numpad key with numlock off, or numlock on and shift on (unicode is set to 0 by SDL or the OS in these circumstances. If numlock is on, unicode is the relevant digit character).
+			// For some unknown reason, event.key.keysym.mod seems to be unreliable on some computers (keysum.mod&KEY_MOD_NUM is opposite to the actual value), so check keysym.unicode instead.
+			// Note: unicode is always zero for SDL_KEYUP events, so this translation won't always work properly for keyup events.
 			SDLKey newKey = MapNumpad(event.key.keysym.sym);
 			if (newKey != event.key.keysym.sym)
 			{
 				event.key.keysym.sym = newKey;
 				event.key.keysym.unicode = 0;
 			}
 		}
+	}
 	switch (event.type)
 	{
 	case SDL_QUIT:

src/gui/interface/Textbox.cpp

@@ -302,11 +302,8 @@ void Textbox::Tick(float dt)
 
 void Textbox::OnKeyRelease(int key, Uint16 character, bool shift, bool ctrl, bool alt)
 {
-	if (keyDown == key)
-	{
-		keyDown = 0;
-		characterDown = 0;
-	}
+	keyDown = 0;
+	characterDown = 0;
 }
 
 void Textbox::OnKeyPress(int key, Uint16 character, bool shift, bool ctrl, bool alt)