Shakespeare is much on Stephen's mind on June 16—he thinks of Hamlet, Macbeth, King Lear, and Antony and Cleopatra in Proteus, and is readying himself to reference dozens of the Bard's works in Scylla and Charybdis—so it is hard not to hear allusions to Twelfth Night when he associates the unnamed young woman whom he saw through Hodges Figgis' window with "kickshaws" and "yellow stockings." Both details imply dislike.
"Kickshaws" is a mocking English rendition of the French quelque choses, "certain things." Sir Toby Belch uses the word when the foolish Sir Andrew Aguecheek confesses that "I delight in masques and revels sometimes altogether." Toby responds, "Art thou good at these kickshawses, knight?" (1.3). The word came into English at about the time of Shakespeare's play, according to the OED, meaning either a fancy cookery dish ("with contemptuous force"), or "something dainty or elegant, but insubstantial or comparatively valueless." Such elegant but trivial French inventions, encountered not only on the dinner table but on the stage as well, elicit disdain from right-thinking Englishmen.
"Yellow stockings," cross-gartered, are another such pretentious innovation, despised by the no-nonsense Lady Olivia but unfortunately adopted by her steward, Malvolio, in a misguided attempt to win her favor. In the context of Stephen's thoughts, they imply sexual unattractiveness—an exotic anaphrodisiac to accompany the more mundane "lumpy wool" and "those curse of God stays suspenders," a corset with garters that invites God's curse, Gifford supposes, because it may function as a chastity belt. As Maria says to Sir Toby, relishing her brilliant joke, "He will come to her in yellow stockings, and ’tis a color she abhors, and cross-gartered, a fashion she detests" (2.5).
Putting these pieces together, one may assume that the literary Stephen is finding reasons to second-guess his attraction to the virgin at the window, by despising her upper-class affectations. Bloom will experience a similar moment of distaste when he sees a young woman chatting up George Russell: "Her stockings are loose over her ankles. I detest that: so tasteless. Those literary etherial people they are all. Dreamy, cloudy, symbolistic. Esthetes they are."