vcl: copyBits should operate on mrParent if no context supplied.

eg. OutputDevice::DrawOutDev:
            mpGraphics->CopyBits( aPosAry, NULL, this, NULL );

Change-Id: I0b041bb5aa6aba573b9f589842084722481cb438
vcl: always use the default windows' GL Context for now to create bitmaps.

Change-Id: Ie20b10656788113709b0b0720d3cae2653639d78
vcl: Implement drawing of transformed bitmaps in OpenGL backend

Change-Id: I79717a608f33050b84244e378a6e51bd3be29232
vcl: Fix DrawMask implementation in OpenGL backend

Change-Id: Idc0bedaba5a4cea351f131d402c2b1093ac1c53c
vcl: only use default windows' GL Context for bitmaps if NULL / uninitialized.

Change-Id: I6465c548ba5d50da2cca7cce24e9bd2a20b28f47
vcl: initialize data when XGetWindowAttributes fails.

Change-Id: If6fc99483c06efec9a600226a09ead9a3f6dab59