The availability of numerous UI components, the promise of accessibility, and cross-platform support have made UI frameworks (e.g., Flutter, Xamarin, React Native) and libraries (e.g., wxPython) quite popular among software developers. However, their widespread use also highlights the need to understand the experiences of programmers with visual impairments with them. We adopted a mixed-methods design comprising two studies to understand the accessibility and challenges of developing interfaces with UI frameworks and libraries. In Study 1, we analyzed 96 randomly-sampled archived threads of Program-L, a mailing list primarily comprising programmers with visual impairments. In Study 2, we interviewed 18 programmers with visual impairments to confirm the findings from Study 1 and gain a deeper understanding of their motivations and experiences in using UI frameworks. Our participants considered UI development essential to their programming responsibilities and sought to acquire relevant skills and expertise. However, accessibility barriers in programming tools and UI frameworks complicated the processes of writing UI code, debugging, testing, and collaborating with sighted colleagues. Our paper concludes with recommendations grounded in empirical findings to improve the accessibility of frameworks and libraries.