[LyX/master] Add comment

[Enrico Forestieri]

commit f51662928579db1e44bd0fb024e6b65eb02f6add
Author: Enrico Forestieri <for...@lyx.org>
Date:   Tue Mar 31 01:26:48 2015 +0200

    Add comment

diff --git a/src/insets/InsetInfo.cpp b/src/insets/InsetInfo.cpp
index ac2fd03..9a9fc14 100644
--- a/src/insets/InsetInfo.cpp
+++ b/src/insets/InsetInfo.cpp
@@ -420,6 +420,10 @@ void InsetInfo::updateInfo()
                        break;
                int percent_scale = 100;
                if (use_gui) {
+                       // Compute the scale factor for the icon such its
+                       // width on screen is equal to 1em in pixels.
+                       // The scale factor is rounded to the integer nearest
+                       // to the float value of the ratio 100*iconsize/imgsize.
                        int imgsize = 
QImage(toqstr(file.absFileName())).width();
                        if (imgsize > 0) {
                                int iconsize = Length(1, 
Length::EM).inPixels(1);