The PC is able to illogically perform several actions while stuck in webs. The webs themselves also have some quirks.
The PC is not restricted from performing several actions while stuck in webs. The webs themselves also have some certain idiosyncrasies.
(1) Wands can be zapped while stuck in webs.
(2) Potions can be drunk while stuck in webs.
(3) Instruments can be played while stuck in webs.
(4) Acid Ball and Lightning Ball destroy webs, but Acid Bolt and Lightning Bolt do not.
(5) The Web spell and wands of webbing won't create webs on trapped squares, whether the PC knows there's a trap there or not. This is abusable.
(6) You can dig through walls while stuck in webs (also while confused and stunned).
(7) "Casting 'Burning Hands' while trapped in a web is supposed to damage you, but you cannot cast any spells while trapped in webs." -- sorear's wiki. Not being able to use magic if in webs is fine, so the possibility of dying this way should probably be removed from the code.
(8) The Web spell and wands of webbing won't create webs in door tiles, but spiders can. The doors can then be opened and closed, with the web not being a problem, and always displayed over it.
(9) (Might be related to #8) I once found the closed door to a room where spiders were locked being displayed with the same color as webs, but stupidly didn't create a savegame to report it.
You can do all of the following while stuck in webs:
(10) 'o'pen, 'c'lose, lock and unlock (\Cu) doors.
(11) Clean your 'E'ars.
(12) Dip something into a potion ('!').
(13) 'g'ive items to someone/thing else.
(14) 'k'ick stuff around.
(15) Wipe your 'F'ace.
(16) 'u'se torches, whips, magical writing sets, instruments and herbs in (maybe other items) the tool slot. Meaning entry #3 doesn't seem to be fixed.
(17) 'U'sing magical writing sets (maybe other items too).
(18) 'p'aying for items.
(19) Breaking webs by walking against a wall or towards water doesn't use a turn.
(20) Using the continuous search (ws) command while stuck in webs results in a barrage of "You fail to search due to the webs" messages, as if the player had used the regular 's'earch command a few dozen times.
j.t.: did Thomas confirm point #1 was a bug? I just had the following exchange with a PC that zapped a wand of wonder while stuck in webs.
This wand forces you to cast some spell! You focus your magical energies to release the spell. Do you want to burn the webs? [y/N]
You completely burn the webs in your vicinity.
In the process you get scorched a bit, too. You resist the searing flames.
Which would make #7 not a bug. A part of me now believes wand zapping is intentional and the scorching damage is yet another display of genius from TB's side :D