always show checkbox when selected, also in IE8, fix #1621

apps/files/css/files.css

@@ -87,9 +87,14 @@ table td.filename .nametext, .uploadtext, .modified { float:left; padding:.3em 0
 table td.filename .nametext { overflow:hidden; text-overflow:ellipsis; }
 table td.filename .uploadtext { font-weight:normal; margin-left:.5em; }
 table td.filename form { font-size:.85em; margin-left:3em; margin-right:3em; }
+
+/* File checkboxes */
 #fileList tr td.filename>input[type="checkbox"]:first-child { -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=0)"; filter:alpha(opacity=0); opacity:0; float:left; margin:.7em 0 0 1em; /* bigger clickable area doesn’t work in FF width:2.8em; height:2.4em;*/ -webkit-transition:opacity 200ms; -moz-transition:opacity 200ms; -o-transition:opacity 200ms; transition:opacity 200ms; }
 #fileList tr td.filename>input[type="checkbox"]:hover:first-child { -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=80)"; filter:alpha(opacity=80); opacity:.8; }
+/* Always show checkbox when selected */
 #fileList tr td.filename>input[type="checkbox"]:checked:first-child { -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=100)"; filter:alpha(opacity=100); opacity:1; }
+#fileList tr.selected td.filename>input[type="checkbox"]:first-child { -ms-filter:"progid:DXImageTransform.Microsoft.Alpha(Opacity=100)"; filter:alpha(opacity=100); opacity:1; }
+
 #fileList tr td.filename {
 	position:relative; width:100%;
 	-webkit-transition:background-image 500ms; -moz-transition:background-image 500ms; -o-transition:background-image 500ms; transition:background-image 500ms;