Mouse- and Keyboard-driven handling:

Move:

Click & Drag

Rotate clockwise in steps of 90°:

DoubleClick

Flip along X-axis:

DoubleClick & [alt]Key or Right Mouse Button

Flip along Y-axis:

DoubleClick & [shift]Key or Middle Mouse Button

Keyboard-driven handling: (if focused through mouse over image)

Reset:

Press [escape]

Mixup:

Press [delete] or [backspace]

Solve (animated):

Press [return] or [enter]