General theme

Move over images and tabs to handle application interaction. In several features, the
image the mouse is over, will become the active context (user interest).
When hovering an image (single mode or compare mode), one can notice the status bar
info changes accordingly (same goes for tab info).

Ctrl + Scroll

Zoom in / out. Synonyms of [+] / [-].

Scroll (wheel)

Scroll up / down.

Shift + Scroll

Scroll left / right.

Left click on tab X (top-left of the tab)

Close the current open image. If in Compare mode, you can hold the Ctrl while hovering
the X icon and it will change to O, then, L-Click will remove the image from the
comparison party rather than the default close behavior.

Left click in tab

Show an image histogram + statistics summary. See Histogram view for further info.
L-Click again on the tab to close the Histogram overlay.

Left click in image

First click, selects ROI (Region-of-interest) Top-Left coordinate. Second, selects
Bottom-Right coordinate and make the Selection Mode active. If in Compare Mode, all
images are selected simultaneously. If you enter Compare mode while party images have
different active ROI, only de-selection will have meaning otherwise the behavior is
unpredictable (but might be useful to compare different histogram datum).
While in ROI 2nd coordinate selection phase, you will see at the status bar the anchor
coordinate with the anticipated ROI size, presuming your current position will be
final.

Right click in image

Disables the current active ROI selection and returns to full image view.
If you hover an active ROI corner (lit with white filled circle), R-Click will assume
you wish to adjust this corner so you will restart your ROI selection while the
diagonal point will become the anchor point (so you can re-adjust the current
position).