fix a warning message in PaletteData class
tweak the progress dialog to make it cannot be cancelled
change option button's pressed appearance in palette item view
add "View" option for Palette Item options
works:
1.fix the issue that the palette item in list view is not clickable
2.add handling logic for palette item click / long click
3.add tweak palette item appearance to make it have a highlight bg when
it is clicked