Bug 355336

This is a wishbug for changing layer blend mode with shortcuts,
there was a discussion on the forums about this 
you can view the discussion here -> https://forum.kde.org/viewtopic.php?f=288&t=129101&p=345604

basically we already have blend mode shortcuts for brush , we can extend this to layer blend-mode by making it tool specific. 
For example if the move tool is selected and user presses ALT +SHIFT + M the layer blending mode will be changed to multiply, and if the user has brush or painting tools active the brush blending modes changes to multiply leaving the layer blending mode as is.

This is how photoshop does it too, making the shortcut tool specific will be helpful to user coming from photoshop.

So to summarize it will be like this
- change layer blending mode with existing shortcuts when the move tool is active.
-change brush blending mode when the brush tools ( painting tools) are active.

Reproducible: Always