"Inline rename" breakpoint accepts spaces & shows garbage if theming is disabled

[iloveeclipse]

1. Disable Themes for Eclipse (Uncheck "Preferences -> General -> Appearance -> Enable theming")
2. In Breakpoints view, select any breakpoint and hit F2 to rename
3. The view shows some garbage over the selected breakpoint. On closer look, it is extra label that explains the breakpoint can be renamed which overlaps with breakpint label above :

4. Once this is fixed, next issue appears: one can specify whitespace as breakpoint labels which makes it "invisible" :

I have trivial patches for both issues.

[iloveeclipse]

Not a regression, it is original code from #1803.