I suggest a feature that would place all elements into small groups. A small triangle would appear next to any elements in these groups. When clicked, it would popup the other elements in the group. For example,

WATER
SNOW
ICE
WTRV

would all be in the same group.

O2
LO2

would be in the same group.

This would let users navigate the menu by particle type (solid, gas, liquid) and yet be able to access closely-related elements without switching to another group. Perhaps CTRL-TAB would switch between elements of the primary element's group? CTRL-TAB would switch to the element's category and pop open the elements group, switching the red border to the current element selected. Nothing would occur if the element is not in a group (e.g., STKM).

No. A sub-category would be limited to elements within the super-category, but the groups I am suggesting are on the same level as the categories.

Reshiram
Yeah, that's what I was thinking. Forgot about DSTW and SLTW though.