Gvim Font-glitches for combining characters (pango-view has no problems) in "Ubuntu Mono" font

[GoogleCodeExporter]

What steps will reproduce the problem?
1.
Consider a text file with one line:
----á----
i.e. between the "minus signs": U+0061 U+0301 (g8: 61 + cc 81)
2. gvim -u NONE -U NONE -N  -c 'set gfn=Ubuntu\ Mono\ 30'

What is the expected output? What do you see instead?
The expected output: the same es the output of 
pango-view -t "----á-----" --font="Ubuntu mono 65"
There is a screen-shot attached with the output of Gvim and the expected output 
(of pango-view).

This problem does not occur with e.g.
se gfn=Bitstream\ Vera\ Sans\ Mono\ Bold\ 12

What version of the product are you using? On what operating system?
Gvim 7.4.826 on Fedora 22

Please provide any additional information below.

VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Aug 14 2015 13:47:52)
Included patches: 1-207, 209-826
Huge version with GTK2 GUI.  Features included (+) or not (-):
+acl             -ebcdic          +localmap        +printer         +title
+arabic          +emacs_tags      -lua             +profile         +toolbar
+autocmd         +eval            +menu            +python/dyn      
+user_commands
+balloon_eval    +ex_extra        +mksession       -python3         +vertsplit
+browse          +extra_search    +modify_fname    +quickfix        +virtualedit
++builtin_terms  +farsi           +mouse           +reltime         +visual
+byte_offset     +file_in_path    +mouseshape      +rightleft       +visualextra
+cindent         +find_in_path    +mouse_dec       +ruby/dyn        +viminfo
+clientserver    +float           +mouse_gpm       +scrollbind      +vreplace
+clipboard       +folding         -mouse_jsbterm   +signs           +wildignore
+cmdline_compl   -footer          +mouse_netterm   +smartindent     +wildmenu
+cmdline_hist    +fork()          +mouse_sgr       -sniff           +windows
+cmdline_info    +gettext         -mouse_sysmouse  +startuptime     +writebackup
+comments        -hangul_input    +mouse_urxvt     +statusline      +X11
+conceal         +iconv           +mouse_xterm     -sun_workshop    -xfontset
+cryptv          +insert_expand   +multi_byte      +syntax          +xim
+cscope          +jumplist        +multi_lang      +tag_binary      
+xsmp_interact
+cursorbind      +keymap          -mzscheme        +tag_old_static  
+xterm_clipboard
+cursorshape     +langmap         +netbeans_intg   -tag_any_white   -xterm_save
+dialog_con_gui  +libcall         +path_extra      -tcl             +xpm
+diff            +linebreak       +perl            +terminfo        
+digraphs        +lispindent      +persistent_undo +termresponse    
+dnd             +listcmds        +postscript      +textobjects     
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H -DFEAT_GUI_GTK  -pthread 
-I/usr/include/gtk-2.0 -I/usr/lib64/gtk-2.0/include -I/usr/include/pango-1.0 
-I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/pixman-1 
-I/usr/include/libdrm -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libpng16 
-I/usr/include/pango-1.0 -I/usr/include/harfbuzz -I/usr/include/pango-1.0 
-I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/freetype2 
-I/usr/include/libpng16 -I/usr/include/freetype2 -I/usr/include/libpng16    -O2 
-g -pipe -Wall -Werror=format-security -fexceptions -fstack-protector-strong 
--param=ssp-buffer-size=4 -grecord-gcc-switches  -m64 -mtune=generic 
-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1      

Linking: gcc   -L. -Wl,-z,relro -fstack-protector -rdynamic -Wl,-export-dynamic 
-Wl,--enable-new-dtags  -Wl,-z,relro  -L/usr/local/lib -Wl,--as-needed -o vim   
-lgtk-x11-2.0 -lgdk-x11-2.0 -lpangocairo-1.0 -latk-1.0 -lcairo -lgdk_pixbuf-2.0 
-lgio-2.0 -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lglib-2.0 -lfontconfig 
-lfreetype  -lSM -lICE -lXpm -lXt -lX11 -lSM -lICE  -lm -lnsl  -lselinux  
-lncurses -lacl -lattr -lgpm -ldl   -Wl,--enable-new-dtags  -fstack-protector 
-L/usr/local/lib  -L/usr/lib64/perl5/CORE -lperl -lresolv -lnsl -ldl -lm 
-lcrypt -lutil -lpthread -lc        

Original issue reported on code.google.com by [email protected] on 16 Aug 2015 at 7:29

Attachments:

• GvimUbuntuFontProblem.png

[GoogleCodeExporter]

The dotted circle looks like the glyph for U+25CC.

Original comment by [email protected] on 16 Aug 2015 at 9:11