When you mouse-over a reference picture, two controls appear next to the pin - a magnifying glass and a cross. If you drag left-right on the magnifying glass the reference picture will zoom. If you drag around on the cross the reference image will pan its contents.
Note that you can only pan the contents if you've zoomed in some.
So first click on the magnifying-glass and drag to the right a bit. Then click on the cross and drag around to get to the detail in the reference image you want.
The menus and palettes in ArtRage are dismissed on right-click in the canvas, or by pressing 'Enter'. (They're also retracted by pressing 'Tab').
It's likely you're either clicking the right-click button on your stylus while you're working, or you're accidentally hitting one of the buttons on the front panel of the TabletPC which is mapped to the 'Enter' or 'Tab' keys.
The mixing-palette colour-swatch pane was just a mock-up done as part of someone's wish-list for features here.
Note however that you can use a portion of your canvas for colour-mixing, then use the 'Custom Colour-picker' menu to capture that portion of your canvas and place it in the colour picker.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"