diff --git a/build_file.c b/build_file.c
index 8b25a77..55c9799 100644
--- a/build_file.c
+++ b/build_file.c
@@ -41,19 +41,18 @@ void build_testing_target(void) {
 
         ok = os_systemf("testing.exe");
         if (ok != 0) exit(ok);
+    } else {
+        int ok = os_systemf(
+            "clang ../src/testing/testing_main.c -o testing.exe -g -I ../src"
+            " -fdiagnostics-absolute-paths -Wno-unsequenced -Wno-single-bit-bitfield-constant-conversion"
+            " -lm -ldl"
+        );
+        if (ok != 0) exit(ok);
 
-        return;
+        ok = os_systemf("./testing.exe");
+        if (ok != 0) exit(ok);
     }
 
-    int ok = os_systemf(
-        "clang ../src/testing/testing_main.c -o testing.exe -g -I ../src"
-        " -fdiagnostics-absolute-paths -Wno-unsequenced -Wno-single-bit-bitfield-constant-conversion"
-        " -lm -ldl"
-    );
-    if (ok != 0) exit(ok);
-
-    ok = os_systemf("./testing.exe");
-    if (ok != 0) exit(ok);
 }
 
 void build_win32_app_base_target(void) {
@@ -165,13 +164,13 @@ int main(int argc, char **argv) {
     generate_testing_code(tcx->temp);
     generate_text_editor_code(tcx->temp);
 
-    b32 run_server = false;
     b32 run_win32_app_base_target = true;
     b32 run_testing_target = true;
-    b32 run_text_editor_dll_target = false;
+    b32 run_text_editor_dll_target = true;
     b32 run_prototype_dll_target = false;
     b32 run_prototype_wasm_target = false;
     b32 run_prototype_standalone_target = false;
+    b32 run_server = false;
 
     if (run_server) {
         os_systemf("start /D ..\\package ..\\package\\run_server.bat");
diff --git a/src/core/core.c b/src/core/core.c
index ef4c042..87a96d5 100644
--- a/src/core/core.c
+++ b/src/core/core.c
@@ -3,11 +3,14 @@
 #elif PLATFORM_WINDOWS
     #pragma comment(lib, "user32.lib")
     #pragma comment(lib, "DbgHelp.lib")
+    #pragma comment(lib, "Shell32.lib")
+    #pragma comment(lib, "Ole32.lib")
     #define NOMINMAX
     #define WIN32_LEAN_AND_MEAN
     #include <windows.h>
     #include <TlHelp32.h>
     #include <DbgHelp.h>
+    #include <Shlobj.h>
     #include <math.h>
     #include <string.h>
     #include <stdio.h>
@@ -59,6 +62,7 @@
 #include "core_type_info.c"
 #include "core_hash.c"
 #include "core_hash_table.c"
+#include "core_array.c"
 #ifndef DONT_INCLUDE_GENERATED_MATH
 #include "core_math.gen.c"
 #endif
diff --git a/src/core/core_array.c b/src/core/core_array.c
new file mode 100644
index 0000000..455d24a
--- /dev/null
+++ b/src/core/core_array.c
@@ -0,0 +1,98 @@
+typedef struct array_header_t array_header_t;
+struct array_header_t {
+    ma_arena_t *arena;
+    i64 len;
+    i64 cap;
+};
+
+#define array_header(arr) ((array_header_t *)(arr) - 1)
+#define array_len(arr) (array_header(arr)->len)
+#define array_cap(arr) (array_header(arr)->cap)
+#define array_add(arr, x) (array_grow(&(arr), sizeof(*(arr)), 1), (arr)[array_len(arr)++] = (x))
+#define array_addn(arr, count) (array_grow(&(arr), sizeof(*(arr)), (count)), array_len(arr) += (count), &(arr)[array_len(arr) - (count)])
+#define array_set_len(arr, x) (array_len(arr) = (x))
+#define array_set_cap(arr, x) (array__set_cap(&(arr), sizeof(*(arr)), (x)))
+#define array_pop(arr) ((arr)[--array_len(arr)])
+#define array_swapdel(arr, i) (assert_expr((i) < array_len(arr)), (arr)[(i)] = (arr)[--array_len(arr)])
+#define array_create(arena, type, count) (type *)(array__create((arena), sizeof(type), (count)) + 1)
+
+fn array_header_t *array__create(ma_arena_t *arena, i64 item_size, i64 item_count) {
+    array_header_t *hdr = (array_header_t *)ma_push_size(arena, item_size * item_count + sizeof(array_header_t));
+    hdr->arena = arena;
+    hdr->cap = item_count;
+    return hdr;
+}
+
+fn void array__set_cap(void **arr, i64 item_size, i64 item_count) {
+    array_header_t *hdr = array_header(*arr);
+    array_header_t *new_hdr = array__create(hdr->arena, item_size, item_count);
+    new_hdr->len = CLAMP(hdr->len, 0, item_count);
+    memory_copy(new_hdr + 1, hdr + 1, new_hdr->len * item_size);
+    *arr = new_hdr + 1;
+}
+
+fn void array_grow(void **arr, i64 item_size, i64 increment) {
+    assert(increment >= 1);
+    array_header_t *hdr = array_header(*arr);
+    if (hdr->len + increment > hdr->cap) {
+        array_header_t *new_hdr = array__create(hdr->arena, item_size, (hdr->cap + increment - 1) * 2);
+        memory_copy(new_hdr + 1, hdr + 1, hdr->len * item_size);
+        new_hdr->len = hdr->len;
+        *arr = new_hdr + 1;
+        // dealloc(hdr);
+    }
+}
+
+fn_test void test_array(void) {
+    ma_temp_t scratch = ma_begin_scratch();
+    int *arr = array_create(scratch.arena, int, 2);
+    for (int i = 0; i < 512; i += 1) {
+        array_add(arr, i);
+    }
+    for (int i = 0; i < 512; i += 1) {
+        assert(arr[i] == i);
+    }
+    assert(array_len(arr) == 512);
+    assert(array_cap(arr) == 512);
+    for (int i = 511; i >= 0; i -= 1) {
+        int a = array_pop(arr);
+        assert(a == i);
+    }
+    assert(array_len(arr) == 0);
+
+    {
+        int *a = array_addn(arr, 4);
+        assert(arr == a);
+        assert(array_header(arr)->len == 4);
+
+        int *b = array_addn(arr, 12);
+        assert(arr + 4 == b);
+        assert(array_header(arr)->len == 16);
+
+        array_set_len(arr, 0);
+    }
+
+    {
+        for (int i = 0; i < 512; i += 1) {
+            array_add(arr, i);
+        }
+
+        array_swapdel(arr, 3);
+        assert(arr[3] == 511);
+        assert(array_len(arr) == 511);
+
+        array_set_len(arr, 0);
+    }
+
+    {
+        for (int i = 0; i < 512; i += 1) {
+            array_add(arr, i);
+        }
+        array_set_cap(arr, 256);
+        assert(array_len(arr) == 256);
+        assert(array_cap(arr) == 256);
+    }
+
+
+    ma_end_scratch(scratch);
+}
diff --git a/src/core/core_lexer.c b/src/core/core_lexer.c
index 6095cf1..2bbe749 100644
--- a/src/core/core_lexer.c
+++ b/src/core/core_lexer.c
@@ -432,7 +432,7 @@ fn void parser_panicf(b32 print_only_file, lex_t *token, const char *str, ...) {
     if (print_only_file) {
         fatalf("%s: error: %S", token->file, str8);
     } else {
-        fatalf("%S(%d): error: %S", token->file, token->line, str8);
+        fatalf("%s(%d): error: %S", token->file, token->line, str8);
     }
 
 
diff --git a/src/os/os_win32.c b/src/os/os_win32.c
index f4ef992..22abd69 100644
--- a/src/os/os_win32.c
+++ b/src/os/os_win32.c
@@ -363,4 +363,33 @@ fn i32 os_thread_join(os_thread_t *thread) {
 //         os_thread_join(&threads[i]);
 //     }
 //     ma_end_scratch(scratch);
-// }
\ No newline at end of file
+// }
+
+fn s8_t os_appdata(ma_arena_t *arena, s8_t name) {
+    assert(name.len != 0);
+    assert(name.str);
+    assert(arena);
+
+    wchar_t *out_path = NULL;
+    HRESULT hr = SHGetKnownFolderPath(&FOLDERID_RoamingAppData, KF_FLAG_CREATE, NULL, &out_path);
+    if (!SUCCEEDED(hr)) {
+        debugf(__FUNCTION__".SHGetKnownFolderPath failed with hr: %d", hr);
+        return s8_null;
+    }
+
+    s16_t appdata_path = s16_from_str16((u16 *)out_path);
+
+    ma_temp_t scratch = ma_begin_scratch1(arena);
+    s8_t tmp = s8_from_s16(scratch.arena, appdata_path);
+    s8_normalize_path_unsafe(tmp);
+    s8_t path = s8_printf(arena, "%S/%S/", tmp, name);
+    os_mkdir_t mkdir_status = os_mkdir(path);
+    if (mkdir_status != os_mkdir_success && mkdir_status != os_mkdir_file_exists) {
+        debugf(__FUNCTION__".os_mkdir failed with status: %d, for: %S", mkdir_status, path);
+        path = s8_null;
+    }
+
+    CoTaskMemFree(out_path);
+    ma_end_scratch(scratch);
+    return path;
+}
\ No newline at end of file
diff --git a/src/testing/testing.gen.c b/src/testing/testing.gen.c
index 1b1b98a..d58ccd4 100644
--- a/src/testing/testing.gen.c
+++ b/src/testing/testing.gen.c
@@ -1,5 +1,10 @@
+void test_string16(void);
+void test_hash_table(void);
+void test_intern_table(void);
+void test_array(void);
 fn void run_tests(void) {
     test_string16();
     test_hash_table();
     test_intern_table();
+    test_array();
 }
diff --git a/src/testing/testing.meta.c b/src/testing/testing.meta.c
index 3284f2d..19872a5 100644
--- a/src/testing/testing.meta.c
+++ b/src/testing/testing.meta.c
@@ -21,6 +21,9 @@ void generate_testing_code(ma_arena_t *arena) {
     }
 
     sb8_t *c = sb8_serial_begin(arena);
+    for (sb8_node_t *it = tests->first; it; it = it->next) {
+        sb8_printf(c, "void %S(void);\n", it->string);
+    }
     sb8_printf(c, "fn void run_tests(void) {\n");
     for (sb8_node_t *it = tests->first; it; it = it->next) {
         sb8_printf(c, "    %S();\n", it->string);
diff --git a/src/testing/testing_main.c b/src/testing/testing_main.c
index 83c040f..81f53c0 100644
--- a/src/testing/testing_main.c
+++ b/src/testing/testing_main.c
@@ -6,9 +6,12 @@
 #include "testing.gen.c"
 
 fn void os_test(void) {
+    ma_temp_t scratch = ma_begin_scratch();
+
     os_date_t local_time = os_local_time();
     os_date_t universal_time = os_universal_time();
-    debugf("OS local_time = %S | universal_time = %S", os_format_date(tcx->temp, local_time), os_format_date(tcx->temp, universal_time));
+    unused(universal_time); unused(local_time);
+    // debugf("OS local_time = %S | universal_time = %S", os_format_date(tcx->temp, local_time), os_format_date(tcx->temp, universal_time));
 
     s8_t exe_dir = os_exe_dir(tcx->temp);
     assert(exe_dir.str[exe_dir.len - 1] == '/');
@@ -25,11 +28,19 @@ fn void os_test(void) {
     assert(os_is_abs(exe));
     assert(os_is_abs(cwd));
     assert(!os_is_abs(s8("../path/")));
-    debugf("OS paths %S %S %S", exe_dir, exe, cwd);
+    // debugf("OS paths %S %S %S", exe_dir, exe, cwd);
 
     s8_t file = os_read(tcx->temp, s8("../.gitignore"));
     assert(file.str != 0);
     assert(file.len != 0);
+
+#if PLATFORM_WINDOWS
+    s8_t path = os_appdata(scratch.arena, s8("testing"));
+    assert(path.str[path.len - 1] == '/');
+    assert(s8_starts_with(path, s8("C:/")));
+    assert(s8_ends_with(path, s8("/testing/")));
+#endif
+    ma_end_scratch(scratch);
 }
 
 fn void test_s8(void) {
diff --git a/src/text_editor/text_editor.gen.c b/src/text_editor/text_editor.gen.c
index 774cb0e..a6666fc 100644
--- a/src/text_editor/text_editor.gen.c
+++ b/src/text_editor/text_editor.gen.c
@@ -10,5 +10,5 @@ void run_all_tests(void) {
     test_string16();
     test_hash_table();
     test_intern_table();
-    ui_test_text_replace();
+    test_array();
 }// run_all_tests()
diff --git a/src/text_editor/text_editor_main.c b/src/text_editor/text_editor_main.c
index 4b9d4aa..4bf643c 100644
--- a/src/text_editor/text_editor_main.c
+++ b/src/text_editor/text_editor_main.c
@@ -1,21 +1,61 @@
 #include "core/core.h"
 #include "os/os.h"
 #include "app/app.h"
-#include "ui/ui.h"
+// #include "ui/ui.h"
 
 #include "core/core.c"
 #include "os/os.c"
 #include "app/app.c"
 #include "render/render.c"
-#include "ui/ui.c"
+// #include "ui/ui.c"
 
 #include "text_editor.gen.c"
 
-// @todo:
-// Create a complete string16 library
-// Win32 SDL_GetPrefPath, create configuration directory, get path
-// Win32 set screen saver
-// Win32 upload icon
+/*todo:
+ * OK Create a complete string16 library
+ * OK (Win32) Win32 SDL_GetPrefPath, create configuration directory, get path
+ * Array
+ *
+ *
+ *
+ * Win32 upload icon
+**/
+
+typedef struct caret_t caret_t;
+struct caret_t {
+    i64 ifront;
+    union {
+        r1i64_t range;
+        i64 pos[2];
+    };
+};
+
+typedef struct xy_t xy_t;
+struct xy_t {
+    i64 col;
+    i64 line;
+};
+
+typedef struct buffer_id_t buffer_id_t;
+struct buffer_id_t { i64 e; };
+
+typedef struct buffer_t buffer_t;
+struct buffer_t {
+    buffer_id_t id;
+
+    union {
+        s16_t string;
+        struct {
+            u16 *data;
+            i64 len;
+        };
+    };
+    i64 cap;
+
+    i64 *line_starts;
+    i64 line_count;
+};
+
 
 fn_export b32 app_update(thread_ctx_t *thread_ctx, app_frame_t *frame) {
     tcx = thread_ctx;
@@ -40,6 +80,10 @@ fn_export b32 app_update(thread_ctx_t *thread_ctx, app_frame_t *frame) {
         rn_reload_font(font_size, frame->dpr);
     }
 
+    rn_begin_frame(frame);
+    rn_begin(white_color);
+    rn_end();
+
 
     return true;
 }
diff --git a/src/ui/ui.c b/src/ui/ui.c
index bc6e717..281c23f 100644
--- a/src/ui/ui.c
+++ b/src/ui/ui.c
@@ -1293,7 +1293,7 @@ fn void ui_demo_everything_lister(void) {
 
             ma_temp_t scratch = ma_begin_scratch();
             s8_t needle = s8_make(text_input.str, text_input.len);
-            fuzzy_pair_t *pairs = fuzzy_rate_array(scratch.arena, needle, cmds, lengthof(cmds));
+            fuzzy_pair_t *pairs = s8_fuzzy_rate_array(scratch.arena, needle, cmds, lengthof(cmds));
 
             b32 set_focus = lister_just_opened || ti_sig.text_changed;
 
@@ -1370,7 +1370,7 @@ fn void ui_demo_update(app_frame_t *frame, mt_tweak_t *tweak_table, i32 tweak_co
                 ui_top_rectp()[0] = r2f32_shrinks(ui_top_rect(), ui_em(1));
                 for (i32 i = 0; i < tweak_count; i += 1) {
                     mt_tweak_t *tweak = tweak_table + i;
-                    if (s8_starts_with(tweak->name, s8("_"), false)) {
+                    if (s8_starts_with(tweak->name, s8("_"))) {
                         continue;
                     }
 
diff --git a/src/wasm_app/wasm_app.gen.c b/src/wasm_app/wasm_app.gen.c
index 4d1fab2..37bc685 100644
--- a/src/wasm_app/wasm_app.gen.c
+++ b/src/wasm_app/wasm_app.gen.c
@@ -10,5 +10,6 @@ void run_all_tests(void) {
     test_string16();
     test_hash_table();
     test_intern_table();
+    test_array();
     ui_test_text_replace();
 }// run_all_tests()