diff --git a/src/libvterm/include/vterm.h b/src/libvterm/include/vterm.h
new file mode 100644
index 0000000..1aa6463
--- /dev/null
+++ b/src/libvterm/include/vterm.h
@@ -0,0 +1,370 @@
+/*
+ * NOTE: This is a MODIFIED version of libvterm, see the README file.
+ */
+#ifndef __VTERM_H__
+#define __VTERM_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "vterm_keycodes.h"
+
+typedef struct VTerm VTerm;
+typedef struct VTermState VTermState;
+typedef struct VTermScreen VTermScreen;
+
+/* Specifies a screen point. */
+typedef struct {
+  int row;
+  int col;
+} VTermPos;
+
+/*
+ * Some small utility functions; we can just keep these static here.
+ */
+
+/*
+ * Order points by on-screen flow order:
+ * Return < 0 if "a" is before "b"
+ * Return  0  if "a" and "b" are equal
+ * Return > 0 if "a" is after "b".
+ */
+int vterm_pos_cmp(VTermPos a, VTermPos b);
+
+#if defined(DEFINE_INLINES) || USE_INLINE
+INLINE int vterm_pos_cmp(VTermPos a, VTermPos b)
+{
+  return (a.row == b.row) ? a.col - b.col : a.row - b.row;
+}
+#endif
+
+/* Specifies a rectangular screen area. */
+typedef struct {
+  int start_row;
+  int end_row;
+  int start_col;
+  int end_col;
+} VTermRect;
+
+/* Return true if the rect "r" contains the point "p". */
+int vterm_rect_contains(VTermRect r, VTermPos p);
+
+#if defined(DEFINE_INLINES) || USE_INLINE
+INLINE int vterm_rect_contains(VTermRect r, VTermPos p)
+{
+  return p.row >= r.start_row && p.row < r.end_row &&
+         p.col >= r.start_col && p.col < r.end_col;
+}
+#endif
+
+/* Move "rect" "row_delta" down and "col_delta" right.
+ * Does not check boundaries. */
+void vterm_rect_move(VTermRect *rect, int row_delta, int col_delta);
+
+#if defined(DEFINE_INLINES) || USE_INLINE
+INLINE void vterm_rect_move(VTermRect *rect, int row_delta, int col_delta)
+{
+  rect->start_row += row_delta; rect->end_row += row_delta;
+  rect->start_col += col_delta; rect->end_col += col_delta;
+}
+#endif
+
+typedef struct {
+  uint8_t red, green, blue;
+} VTermColor;
+
+typedef enum {
+  /* VTERM_VALUETYPE_NONE = 0 */
+  VTERM_VALUETYPE_BOOL = 1,
+  VTERM_VALUETYPE_INT,
+  VTERM_VALUETYPE_STRING,
+  VTERM_VALUETYPE_COLOR
+} VTermValueType;
+
+typedef union {
+  int boolean;
+  int number;
+  char *string;
+  VTermColor color;
+} VTermValue;
+
+typedef enum {
+  /* VTERM_ATTR_NONE = 0 */
+  VTERM_ATTR_BOLD = 1,   /* bool:   1, 22 */
+  VTERM_ATTR_UNDERLINE,  /* number: 4, 21, 24 */
+  VTERM_ATTR_ITALIC,     /* bool:   3, 23 */
+  VTERM_ATTR_BLINK,      /* bool:   5, 25 */
+  VTERM_ATTR_REVERSE,    /* bool:   7, 27 */
+  VTERM_ATTR_STRIKE,     /* bool:   9, 29 */
+  VTERM_ATTR_FONT,       /* number: 10-19 */
+  VTERM_ATTR_FOREGROUND, /* color:  30-39 90-97 */
+  VTERM_ATTR_BACKGROUND  /* color:  40-49 100-107 */
+} VTermAttr;
+
+typedef enum {
+  /* VTERM_PROP_NONE = 0 */
+  VTERM_PROP_CURSORVISIBLE = 1, /* bool */
+  VTERM_PROP_CURSORBLINK,       /* bool */
+  VTERM_PROP_ALTSCREEN,         /* bool */
+  VTERM_PROP_TITLE,             /* string */
+  VTERM_PROP_ICONNAME,          /* string */
+  VTERM_PROP_REVERSE,           /* bool */
+  VTERM_PROP_CURSORSHAPE,       /* number */
+  VTERM_PROP_MOUSE              /* number */
+} VTermProp;
+
+enum {
+  VTERM_PROP_CURSORSHAPE_BLOCK = 1,
+  VTERM_PROP_CURSORSHAPE_UNDERLINE,
+  VTERM_PROP_CURSORSHAPE_BAR_LEFT
+};
+
+enum {
+  VTERM_PROP_MOUSE_NONE = 0,
+  VTERM_PROP_MOUSE_CLICK,
+  VTERM_PROP_MOUSE_DRAG,
+  VTERM_PROP_MOUSE_MOVE
+};
+
+typedef struct {
+  const uint32_t *chars;
+  int             width;
+  unsigned int    protected_cell:1;  /* DECSCA-protected against DECSEL/DECSED */
+  unsigned int    dwl:1;             /* DECDWL or DECDHL double-width line */
+  unsigned int    dhl:2;             /* DECDHL double-height line (1=top 2=bottom) */
+} VTermGlyphInfo;
+
+typedef struct {
+  unsigned int    doublewidth:1;     /* DECDWL or DECDHL line */
+  unsigned int    doubleheight:2;    /* DECDHL line (1=top 2=bottom) */
+} VTermLineInfo;
+
+typedef struct {
+  /* libvterm relies on the allocated memory to be zeroed out before it is
+   * returned by the allocator. */
+  void *(*malloc)(size_t size, void *allocdata);
+  void  (*free)(void *ptr, void *allocdata);
+} VTermAllocatorFunctions;
+
+/* Allocate and initialize a new terminal with default allocators. */
+VTerm *vterm_new(int rows, int cols);
+
+/* Allocate and initialize a new terminal with specified allocators. */
+VTerm *vterm_new_with_allocator(int rows, int cols, VTermAllocatorFunctions *funcs, void *allocdata);
+
+/* Free and cleanup a terminal and all its data. */
+void   vterm_free(VTerm* vt);
+
+void vterm_get_size(const VTerm *vt, int *rowsp, int *colsp);
+void vterm_set_size(VTerm *vt, int rows, int cols);
+
+int  vterm_get_utf8(const VTerm *vt);
+void vterm_set_utf8(VTerm *vt, int is_utf8);
+
+size_t vterm_input_write(VTerm *vt, const char *bytes, size_t len);
+
+size_t vterm_output_get_buffer_size(const VTerm *vt);
+size_t vterm_output_get_buffer_current(const VTerm *vt);
+size_t vterm_output_get_buffer_remaining(const VTerm *vt);
+
+size_t vterm_output_read(VTerm *vt, char *buffer, size_t len);
+
+void vterm_keyboard_unichar(VTerm *vt, uint32_t c, VTermModifier mod);
+void vterm_keyboard_key(VTerm *vt, VTermKey key, VTermModifier mod);
+
+void vterm_keyboard_start_paste(VTerm *vt);
+void vterm_keyboard_end_paste(VTerm *vt);
+
+void vterm_mouse_move(VTerm *vt, int row, int col, VTermModifier mod);
+void vterm_mouse_button(VTerm *vt, int button, bool pressed, VTermModifier mod);
+
+/* ------------
+ * Parser layer
+ * ------------ */
+
+/* Flag to indicate non-final subparameters in a single CSI parameter.
+ * Consider
+ *   CSI 1;2:3:4;5a
+ * 1 4 and 5 are final.
+ * 2 and 3 are non-final and will have this bit set
+ *
+ * Don't confuse this with the final byte of the CSI escape; 'a' in this case.
+ */
+#define CSI_ARG_FLAG_MORE (1<<31)
+#define CSI_ARG_MASK      (~(1<<31))
+
+#define CSI_ARG_HAS_MORE(a) ((a) & CSI_ARG_FLAG_MORE)
+#define CSI_ARG(a)          ((a) & CSI_ARG_MASK)
+
+/* Can't use -1 to indicate a missing argument; use this instead */
+#define CSI_ARG_MISSING ((1UL<<31)-1)
+
+#define CSI_ARG_IS_MISSING(a) (CSI_ARG(a) == CSI_ARG_MISSING)
+#define CSI_ARG_OR(a,def)     (CSI_ARG(a) == CSI_ARG_MISSING ? (def) : CSI_ARG(a))
+#define CSI_ARG_COUNT(a)      (CSI_ARG(a) == CSI_ARG_MISSING || CSI_ARG(a) == 0 ? 1 : CSI_ARG(a))
+
+typedef struct {
+  int (*text)(const char *bytes, size_t len, void *user);
+  int (*control)(unsigned char control, void *user);
+  int (*escape)(const char *bytes, size_t len, void *user);
+  int (*csi)(const char *leader, const long args[], int argcount, const char *intermed, char command, void *user);
+  int (*osc)(const char *command, size_t cmdlen, void *user);
+  int (*dcs)(const char *command, size_t cmdlen, void *user);
+  int (*resize)(int rows, int cols, void *user);
+} VTermParserCallbacks;
+
+void  vterm_parser_set_callbacks(VTerm *vt, const VTermParserCallbacks *callbacks, void *user);
+void *vterm_parser_get_cbdata(VTerm *vt);
+
+/* -----------
+ * State layer
+ * ----------- */
+
+typedef struct {
+  int (*putglyph)(VTermGlyphInfo *info, VTermPos pos, void *user);
+  int (*movecursor)(VTermPos pos, VTermPos oldpos, int visible, void *user);
+  int (*scrollrect)(VTermRect rect, int downward, int rightward, void *user);
+  int (*moverect)(VTermRect dest, VTermRect src, void *user);
+  int (*erase)(VTermRect rect, int selective, void *user);
+  int (*initpen)(void *user);
+  int (*setpenattr)(VTermAttr attr, VTermValue *val, void *user);
+  int (*settermprop)(VTermProp prop, VTermValue *val, void *user);
+  int (*bell)(void *user);
+  int (*resize)(int rows, int cols, VTermPos *delta, void *user);
+  int (*setlineinfo)(int row, const VTermLineInfo *newinfo, const VTermLineInfo *oldinfo, void *user);
+} VTermStateCallbacks;
+
+VTermState *vterm_obtain_state(VTerm *vt);
+
+void  vterm_state_set_callbacks(VTermState *state, const VTermStateCallbacks *callbacks, void *user);
+void *vterm_state_get_cbdata(VTermState *state);
+
+/* Only invokes control, csi, osc, dcs */
+void  vterm_state_set_unrecognised_fallbacks(VTermState *state, const VTermParserCallbacks *fallbacks, void *user);
+void *vterm_state_get_unrecognised_fbdata(VTermState *state);
+
+void vterm_state_reset(VTermState *state, int hard);
+void vterm_state_get_cursorpos(const VTermState *state, VTermPos *cursorpos);
+void vterm_state_get_default_colors(const VTermState *state, VTermColor *default_fg, VTermColor *default_bg);
+void vterm_state_get_palette_color(const VTermState *state, int index, VTermColor *col);
+void vterm_state_set_default_colors(VTermState *state, const VTermColor *default_fg, const VTermColor *default_bg);
+void vterm_state_set_palette_color(VTermState *state, int index, const VTermColor *col);
+void vterm_state_set_bold_highbright(VTermState *state, int bold_is_highbright);
+int  vterm_state_get_penattr(const VTermState *state, VTermAttr attr, VTermValue *val);
+int  vterm_state_set_termprop(VTermState *state, VTermProp prop, VTermValue *val);
+const VTermLineInfo *vterm_state_get_lineinfo(const VTermState *state, int row);
+
+/* ------------
+ * Screen layer
+ * ------------ */
+
+typedef struct {
+    unsigned int bold      : 1;
+    unsigned int underline : 2;
+    unsigned int italic    : 1;
+    unsigned int blink     : 1;
+    unsigned int reverse   : 1;
+    unsigned int strike    : 1;
+    unsigned int font      : 4; /* 0 to 9 */
+    unsigned int dwl       : 1; /* On a DECDWL or DECDHL line */
+    unsigned int dhl       : 2; /* On a DECDHL line (1=top 2=bottom) */
+} VTermScreenCellAttrs;
+
+typedef struct {
+#define VTERM_MAX_CHARS_PER_CELL 6
+  uint32_t chars[VTERM_MAX_CHARS_PER_CELL];
+  char     width;
+  VTermScreenCellAttrs attrs;
+  VTermColor fg, bg;
+} VTermScreenCell;
+
+/* All fields are optional, NULL when not used. */
+typedef struct {
+  int (*damage)(VTermRect rect, void *user);
+  int (*moverect)(VTermRect dest, VTermRect src, void *user);
+  int (*movecursor)(VTermPos pos, VTermPos oldpos, int visible, void *user);
+  int (*settermprop)(VTermProp prop, VTermValue *val, void *user);
+  int (*bell)(void *user);
+  int (*resize)(int rows, int cols, void *user);
+  int (*sb_pushline)(int cols, const VTermScreenCell *cells, void *user);
+  int (*sb_popline)(int cols, VTermScreenCell *cells, void *user);
+} VTermScreenCallbacks;
+
+VTermScreen *vterm_obtain_screen(VTerm *vt);
+
+/*
+ * Install screen callbacks.  These are invoked when the screen contents is
+ * changed.  "user" is passed into to the callback.
+ */
+void  vterm_screen_set_callbacks(VTermScreen *screen, const VTermScreenCallbacks *callbacks, void *user);
+void *vterm_screen_get_cbdata(VTermScreen *screen);
+
+/* Only invokes control, csi, osc, dcs */
+void  vterm_screen_set_unrecognised_fallbacks(VTermScreen *screen, const VTermParserCallbacks *fallbacks, void *user);
+void *vterm_screen_get_unrecognised_fbdata(VTermScreen *screen);
+
+void vterm_screen_enable_altscreen(VTermScreen *screen, int altscreen);
+
+typedef enum {
+  VTERM_DAMAGE_CELL,    /* every cell */
+  VTERM_DAMAGE_ROW,     /* entire rows */
+  VTERM_DAMAGE_SCREEN,  /* entire screen */
+  VTERM_DAMAGE_SCROLL   /* entire screen + scrollrect */
+} VTermDamageSize;
+
+void vterm_screen_flush_damage(VTermScreen *screen);
+void vterm_screen_set_damage_merge(VTermScreen *screen, VTermDamageSize size);
+
+void   vterm_screen_reset(VTermScreen *screen, int hard);
+
+/* Neither of these functions NUL-terminate the buffer */
+size_t vterm_screen_get_chars(const VTermScreen *screen, uint32_t *chars, size_t len, const VTermRect rect);
+size_t vterm_screen_get_text(const VTermScreen *screen, char *str, size_t len, const VTermRect rect);
+
+typedef enum {
+  VTERM_ATTR_BOLD_MASK       = 1 << 0,
+  VTERM_ATTR_UNDERLINE_MASK  = 1 << 1,
+  VTERM_ATTR_ITALIC_MASK     = 1 << 2,
+  VTERM_ATTR_BLINK_MASK      = 1 << 3,
+  VTERM_ATTR_REVERSE_MASK    = 1 << 4,
+  VTERM_ATTR_STRIKE_MASK     = 1 << 5,
+  VTERM_ATTR_FONT_MASK       = 1 << 6,
+  VTERM_ATTR_FOREGROUND_MASK = 1 << 7,
+  VTERM_ATTR_BACKGROUND_MASK = 1 << 8
+} VTermAttrMask;
+
+int vterm_screen_get_attrs_extent(const VTermScreen *screen, VTermRect *extent, VTermPos pos, VTermAttrMask attrs);
+
+int vterm_screen_get_cell(const VTermScreen *screen, VTermPos pos, VTermScreenCell *cell);
+
+int vterm_screen_is_eol(const VTermScreen *screen, VTermPos pos);
+
+/* ---------
+ * Utilities
+ * --------- */
+
+VTermValueType vterm_get_attr_type(VTermAttr attr);
+VTermValueType vterm_get_prop_type(VTermProp prop);
+
+void vterm_scroll_rect(VTermRect rect,
+                       int downward,
+                       int rightward,
+                       int (*moverect)(VTermRect src, VTermRect dest, void *user),
+                       int (*eraserect)(VTermRect rect, int selective, void *user),
+                       void *user);
+
+void vterm_copy_cells(VTermRect dest,
+                      VTermRect src,
+                      void (*copycell)(VTermPos dest, VTermPos src, void *user),
+                      void *user);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif