How to check if CTRL is pressed during wx.EVT_SCROLLWIN_LINEDOWN event?

[steve]

Hi,

 

I have a ScrolledWindow. When I click on scroll down button on the scroll bar, I want to check if CTRL key is pressed. I do:

 

self.Bind(wx.EVT_SCROLLWIN_LINEDOWN, self.onScrollClickDown)

def onScrollClickDown(self, event):

	ctrl_is_pressed = event.ControlDown()

But it says EVT_SCROLLWIN_LINEDOWN event doesn't have a ControlDown() attribute.

So how do I check if CTRL is pressed during a EVT_SCROLLWIN_LINEDOWN event?

 

[Tim Roberts]

I can tell you something that is likely to work, but you have to sit through a brief lecture first.

The problem you have here is one of timing.  The EVT_SCROLLWIN_LINEDOWN event is heavily processed.  It started out with a mouse click, but that mouse click was trapped by an event handler in the scrollbar code.  It took a look at exactly where inside its window the click occurred, and then generated its own event.  EVT_SCROLLWIN_LINEDOWN is not trying to tell you that the mouse was clicked in the scrollbar.  It's telling you that a "line down" scroll event occurred.  That event can also be generated by using the cursor keys, which is why it doesn't have the normal click/keystroke methods.  It's a different kind of event.

The bigger problem is user expectations.  Scroll bars need to be simple, reliable and predictable.  They work the way they do because those are the UI standards that have been applied for decades.  When you try to make a tweak like this, you are breaking those expectations.  You need to think very seriously before you alter the way a scrollbar responds.

    def onScrollClickDown(self, event):
        if wx.GetKeyState(wx.WXK_CONTROL):
            print "Control key is down"

-- 
Tim Roberts, ti...@probo.com
Providenza & Boekelheide, Inc.