Bug 398271

Setup 2x 4k monitors.
1 is attached to HDMI and the other to DP to onboard integrated Intel® HD Graphics 4600 (i7-4790) Graphics Video Max Memory 2GB.
Screens are scaled to 2x in Plasma settings in order to produce properly visible graphic elements.

When is selected 'Rectangular Region' and clicked 'Take a New Screenshot' the screens black out and only the crosshair pointer is visible(movable).
There is no recovery apart of switching to another console(eg. ctrl+alt+f2) and pkill spectacle.

When run from Konsole during the same as above selection the following is showing up:

qt.qpa.xcb: QXcbConnection: XCB error: 11 (BadAlloc), sequence: 919, resource id: 113246242, major code: 149 (Unknown), minor code: 2
qt.qpa.xcb: QXcbConnection: XCB error: 9 (BadDrawable), sequence: 920, resource id: 113246251, major code: 149 (Unknown), minor code: 4
qt.qpa.xcb: QXcbConnection: XCB error: 4 (BadPixmap), sequence: 922, resource id: 113246251, major code: 148 (Unknown), minor code: 1
qt.qpa.xcb: QXcbConnection: XCB error: 11 (BadAlloc), sequence: 923, resource id: 113246242, major code: 149 (Unknown), minor code: 2
qt.qpa.xcb: QXcbConnection: XCB error: 9 (BadDrawable), sequence: 924, resource id: 113246253, major code: 149 (Unknown), minor code: 4
qt.qpa.xcb: QXcbConnection: XCB error: 4 (BadPixmap), sequence: 925, resource id: 113246253, major code: 148 (Unknown), minor code: 1
Terminated

All other 'Area' options are working in 2x scaling.
When screens are scaled to 1x Spectacle 'Area' option 'Rectangular Region' works properly.

Expected behaviour: 
When screen/s is/are scaled the 'Area' option 'Rectangular Region' to work.