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doc/en/scripting/builtins/libgui.md

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+# *gui* library
+
+The library contains functions for accessing the properties of UI elements. Instead of gui, you should use an object wrapper that provides access to properties through the __index, __newindex meta methods:
+
+Example:
+
+```lua
+print(document.some_button.text) -- where 'some_button' is an element id
+document.some_button.text = "new text"
+```
+
+```python
+gui.str(text: str, context: str) -> str
+```
+
+Returns translated text.
+
+```python
+gui.get_viewport() -> {int, int}
+```
+
+Returns size of the main container (window).
+
+```python
+gui.get_env(document: str) -> table
+```
+
+Returns environment (global variables table) of the specified document.
+
+```lua
+gui.get_locales_info() -> table of tables {
+  name: str
+ }
+-- where
+--   key - locale id following isolangcode_ISOCOUNTRYCODE format
+--   value - table {
+--       name: str # locale display name
+--   }
+```
+
+Returns information about all loaded locales (res/texts/\*).