Web Inspector: AX: Support increased contrast mode

[Timothy Hatcher]

Created attachment 258508 [details]
Screenshot

We should make our toolbar, borders, etc. match the AppKit controls when increased contrast is enabled in Accessibility system preferences. See screenshot.

[Nikita Vasilyev]

How do we detect in Web Inspector that the increased contrast mode is turned on? Can we set something like "increased-contrast-mode" CSS class name on body?

[Timothy Hatcher]

Yeah, we would need to add a class. We would likely add a function on InspectorFrontEndHost to return the state of this mode. I'm not sure what API to use to know when you are in that mode. We also need to know when it changes to update the Inspector live.

[Matt Baker]

For OS X, AppKit's NSWorkspace class exposes the accessibilityDisplayShouldIncreaseContrast property and 
NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification notification.

For the Windows port, winuser.h defines the SystemParametersInfo function:

HIGHCONTRAST highContrast;
highContrast.cbSize = sizeof(HIGHCONTRAST);
SystemParametersInfo(SPI_GETHIGHCONTRAST, sizeof(HIGHCONTRAST), & highContrast, 0);

As for detecting changes, I think we'd want to handle the WM_SETTINGCHANGE message, which is sent to all top-level windows when a system parameter changes. But I'm not positive about this.

[David Kilzer (:ddkilzer)]

<rdar://problem/28228734>