[LyX/master] Set minimal width of fixedwidth collapsable insets.

[Pavel Sanda]

commit 7a5eff56b0498f478eb2120445bcf892cb809f41
Author: Pavel Sanda <sa...@lyx.org>
Date:   Wed Oct 7 02:15:35 2015 -0700

    Set minimal width of fixedwidth collapsable insets.
    
    Intention behind this is actually Box inset being too tiny
    to reasonably contain other insets like ERT.
    
    http://www.mail-archive.com/lyx-devel@lists.lyx.org/msg188987.html

diff --git a/src/insets/InsetCollapsable.cpp b/src/insets/InsetCollapsable.cpp
index 623cebb..d656d7a 100644
--- a/src/insets/InsetCollapsable.cpp
+++ b/src/insets/InsetCollapsable.cpp
@@ -213,6 +213,11 @@ void InsetCollapsable::metrics(MetricsInfo & mi, Dimension 
& dim) const
        case TopButton:
        case LeftButton:
        case ButtonOnly:
+               if (hasFixedWidth()){
+                       const int mindim=button_dim.x2-button_dim.x1;
+                       if (mi.base.textwidth<mindim)
+                               mi.base.textwidth=mindim;
+               }
                dim = dimensionCollapsed(bv);
                if (geometry(bv) == TopButton 
                          || geometry(bv) == LeftButton) {