wxGUI: update menu creation explanations (#3920)

gui/wxpython/Makefile

@@ -14,7 +14,7 @@ SRCFILES := $(wildcard icons/*.py xml/*) \
 	mapswipe/*.py modules/*.py nviz/*.py psmap/*.py rdigit/*.py \
 	rlisetup/*.py startup/*.py timeline/*.py vdigit/*.py \
 	vnet/*.py web_services/*.py wxplot/*.py iscatt/*.py tplot/*.py photo2image/*.py image2target/*.py) \
-	wxgui.py README
+	wxgui.py README.md
 
 DSTFILES := $(patsubst %,$(DSTDIR)/%,$(SRCFILES)) \
 	$(patsubst %.py,$(DSTDIR)/%.pyc,$(filter %.py,$(SRCFILES)))

gui/wxpython/README.md

@@ -0,0 +1,69 @@
+# GRASS GIS - wxPython Graphical User Interface (wxGUI)
+
+## 1 - REQUIREMENTS
+
+See `[../../REQUIREMENTS.md](../../REQUIREMENTS.md)`
+
+## 2 - STARTUP WITH GRASS INITIALIZATION
+
+If you want to launch wxPython GUI automatically, start GRASS with
+`--gui` parameter
+
+`$ grass --gui`
+
+## 3 - STARTUP FROM GRASS TERMINAL
+
+Simply run
+
+`$ g.gui wxpython`
+
+from the GRASS terminal.
+
+You can also specify workspace file to load on startup.
+
+`$ g.gui gui=wxpython workspace=myworkspace.gxw`
+
+## 4 - DEBUGGING
+
+To enable GUI debug messages on given level set `WX_DEBUG` environment
+variable, e.g.
+
+`$ g.gisenv set="WX_DEBUG=3"`
+
+## 5 - CLI BASED DISPLAY USAGE
+
+Use command `d.mon` (shell script in `gui/scripts/` directory) to start map
+display:
+
+`GRASS> d.mon wx[0-6]`
+
+After a while, new window should appear. If this is your case, you can now
+add some layers, e.g. a raster layer to the map display:
+
+`GRASS> d.rast aspect`
+
+And try the vector layer, too
+
+`GRASS> d.vect roads`
+
+You should be able to zoom & pan through the map, once the layers are
+displayed. You should be also able to store the display content as well as
+clear the display and start from scratch.
+
+## 6 TRANSLATION HANDLING
+
+Notes:
+
+- Help part of menu entries is coming from the module descriptions
+- The menu is generated by `./tools/build_modules_xml.py`
+
+Update of module description strings in `./xml/menudata.xml`:
+
+- in a GRASS session, run `./tools/update_menudata.py`
+
+From this (updated) `./xml/menudata.xml`, the gettext strings are generated
+via Makefile and stored into the file `menustrings.py`.
+
+While generating the po files in `../../locale/po/` by `../../locale/Makefile`,
+all `.py` files are parsed and the strings are stored in
+`../../locale/po/grasswxpy_XX.po`.