Fix width of debugger header. Draw debugger element outlines underneath windows.

Source/Debugger/CommonSource.h

@@ -47,7 +47,9 @@ em
 h1
 {
 	position: absolute;
-	top: 0px;
+	top: 0;
+	right: 0;
+	left: 0;
 	height: 22dp;
 	padding: 4dp 5dp;
 	color: white;

Source/Debugger/ElementContextHook.cpp

@@ -44,7 +44,7 @@ ElementContextHook::~ElementContextHook()
 void ElementContextHook::Initialise(DebuggerPlugin* _debugger)
 {
 	SetId("rmlui-debug-hook");
-	SetProperty(PropertyId::ZIndex, Property(1'000'001, Property::NUMBER));
+	SetProperty(PropertyId::ZIndex, Property(999'999, Property::NUMBER));
 	debugger = _debugger;
 }