[0.4.13][NTUSER] Fix taskbar panes activation (#2046) (#3294) (#3697) (#3700), [SHELL...

[0.4.13][NTUSER] Fix taskbar panes activation (#2046) (#3294) (#3697) (#3700), [SHELL32] (#4800)

This is a squashed backport of the following commits:
0.4.14-dev-369-g 141cf04239f3049c1c180fb2c6c3aa84b13c8590 (#2046) NTUSER
0.4.15-dev-1126-g 58b0558f94abee52ce1c261063d4f4b884e96310 (#3294) NTUSER
0.4.15-dev-2618-g 32b0cf6fc6b8f5fab33c10c782f40d36feebbedb (#3697) NTUSER
0.4.15-dev-2621-g 59d4c1120310b7c08641cc3aab82072251900d98 (#3700) NTUSER
0.4.15-dev-5242-g e6fb0e0c25d4509bf30a6ad602c9ba7d143cd77a (#4800) SHELL32 Cleanup SHAppBarMessage()

brings us closer to releases/0.4.14

In the older branches it will fix the following bugs (or prevents introducing them):
CORE-14380 'Effective File Search 6.8.1 when you open up the app via desktop link there is no pane in taskbar'
CORE-15655 'Click-N-Type Virtual Keyboard 3.03.0412 has no taskbar pane'
CORE-15669 'DVD Write Now 1.5.12 SP2 setup has no taskbar pane'
CORE-15716 'Photofiltr 7.2.1 has no taskbar pane'
CORE-15731 'Java JRE 6u45 setup, last page of setup has no taskbar pane'
CORE-16030 'Moo0 Audio Recorder - the taskbar icon does not appear'
(CORE-17330 Regression, many installers that should have only 1 taskbar pane, now have 2 of them erroneously)