showall(win) is needed after push!() hbox, cancel, and ok

[xianwenchen]

showall(win) is needed after push!() hbox, cancel, and ok. Otherwise the new GtkButtonBox hbox will not show, nor will the cancel and ok GtkButton's.

[codecov]

Codecov Report

Merging #568 (614eb63) into master (52d2f73) will decrease coverage by 2.47%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #568      +/-   ##
==========================================
- Coverage   50.15%   47.67%   -2.48%     
==========================================
  Files          32       32              
  Lines        2540     2391     -149     
==========================================
- Hits         1274     1140     -134     
+ Misses       1266     1251      -15     

Impacted Files	Coverage Δ
src/GLib/gerror.jl	33.33% <0.00%> (-6.67%)	⬇️
src/cairo.jl	70.00% <0.00%> (-4.29%)	⬇️
src/lists.jl	55.28% <0.00%> (-4.08%)	⬇️
src/text.jl	38.48% <0.00%> (-3.94%)	⬇️
src/layout.jl	23.86% <0.00%> (-3.32%)	⬇️
src/container.jl	44.44% <0.00%> (-3.06%)	⬇️
src/toolbar.jl	75.00% <0.00%> (-2.78%)	⬇️
src/buttons.jl	62.66% <0.00%> (-2.77%)	⬇️
src/theme.jl	72.72% <0.00%> (-2.28%)	⬇️
src/selectors.jl	21.35% <0.00%> (-2.23%)	⬇️
... and 10 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 52d2f73...07b6238. Read the comment docs.