lcdgfx ships a small set of GUI widgets that work on every supported display (mono OLED through 16-bit TFT) and require no dynamic memory. All widgets share the same lifecycle:

display.begin();
display.fill(0x00);
widget.show(display);            // initial render
// ... on user input:
widget.up();   widget.show(display);
widget.down(); widget.show(display);

Widget	Header	Example
`LcdGfxMenu`	`v2/gui/menu.h`	`examples/gui/menu_demo`
`LcdGfxCheckboxMenu`	`v2/gui/checkbox_menu.h`	`examples/gui/checkbox_demo`
`LcdGfxButton`	`v2/gui/button.h`	`examples/gui/button_demo`
`LcdGfxSlider`	`v2/gui/slider.h`	`examples/gui/slider_demo`
`LcdGfxSpinbox`	`v2/gui/spinbox.h`	`examples/gui/spinbox_demo`
`LcdGfxTextEntry`	`v2/gui/text_entry.h`	`examples/gui/text_entry_demo`
`LcdGfxYesNo`	`v2/gui/yesno.h`	`examples/gui/yesno_demo`

Touch

Menus accept touch coordinates through onTouch(x, y) / itemAtPoint(x, y); see examples/gui/menu_touch_demo. Touch samples come from any source — typically the bundled `LcdGfxXpt2046` driver.

UTF-8

LcdGfxTextEntry cycles through a charset you provide. To accept Cyrillic input, point the widget's secondary font at ssd1306xled_font6x8_Cyrillic and feed UTF-8 codepoints — the stateless decoder lives in canvas/font_utf8.h.