BView: scroll horizontally when holding control

... instead of vertically. This actually swaps horizontal and vertical
so if you have a mouse with a fancy 2-axis scroll ball it will swap
the x and y coordinates. (untested)

src/kits/interface/View.cpp

@@ -12,6 +12,7 @@
 
 #include <View.h>
 
+#include <algorithm>
 #include <new>
 
 #include <math.h>
@@ -4417,6 +4418,9 @@ BView::MessageReceived(BMessage* message)
 				if (deltaX == 0.0f && deltaY == 0.0f)
 					break;
 
+				if ((modifiers() & B_CONTROL_KEY) != 0)
+					std::swap(horizontal, vertical);
+
 				if (horizontal != NULL && deltaX != 0.0f)
 					ScrollWithMouseWheelDelta(horizontal, deltaX);