857728 - Garbled animation when mouse is moved away from the 'Go back one page' button!

Status: UNCONFIRMED

(Firefox :: Toolbars and Customization, defect)

Description

[naych]

Attachment: firefox.jpg

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0
Build ID: 20130326150557

Steps to reproduce:

Updated to Firefox version 20 from version 17. 

System data:
{
  "application": {
    "name": "Firefox",
    "version": "20.0",
    "userAgent": "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0",
    "supportURL": "http://support.mozilla.org/1/firefox/20.0/WINNT/en-US/"
  },
  "modifiedPreferences": {
    "accessibility.typeaheadfind.flashBar": 0,
    "browser.cache.disk.capacity": 358400,
    "browser.cache.disk.smart_size.first_run": false,
    "browser.cache.disk.smart_size.use_old_max": false,
    "browser.cache.disk.smart_size_cached_value": 358400,
    "browser.places.smartBookmarksVersion": 4,
    "browser.search.suggest.enabled": false,
    "browser.startup.homepage_override.mstone": "20.0",
    "browser.startup.homepage_override.buildID": "20130326150557",
    "browser.tabs.warnOnClose": false,
    "dom.w3c_touch_events.expose": false,
    "dom.mozApps.used": true,
    "extensions.lastAppVersion": "20.0",
    "font.internaluseonly.changed": false,
    "gfx.direct3d.prefer_10_1": true,
    "network.cookie.prefsMigrated": true,
    "places.history.expiration.transient_optimal_database_size": 167772160,
    "places.history.expiration.transient_current_max_pages": 104858,
    "places.database.lastMaintenance": 1364987011,
    "plugin.disable_full_page_plugin_for_types": "",
    "privacy.cpd.siteSettings": true,
    "privacy.cpd.offlineApps": true,
    "privacy.sanitize.timeSpan": 0,
    "privacy.sanitize.migrateFx3Prefs": true,
    "security.warn_viewing_mixed": false
  },
  "graphics": {
    "numTotalWindows": 1,
    "numAcceleratedWindows": 1,
    "windowLayerManagerType": "Direct3D 10",
    "adapterDescription": "Intel(R) HD Graphics Family",
    "adapterVendorID": "0x8086",
    "adapterDeviceID": "0x0126",
    "adapterRAM": "Unknown",
    "adapterDrivers": "igdumd64 igd10umd64 igd10umd64 igdumdx32 igd10umd32 igd10umd32",
    "driverVersion": "8.15.10.2321",
    "driverDate": "3-6-2011",
    "adapterDescription2": "",
    "adapterVendorID2": "",
    "adapterDeviceID2": "",
    "adapterRAM2": "",
    "adapterDrivers2": "",
    "driverVersion2": "",
    "driverDate2": "",
    "isGPU2Active": false,
    "direct2DEnabled": true,
    "directWriteEnabled": true,
    "directWriteVersion": "6.2.9200.16492",
    "webglRenderer": "Google Inc. -- ANGLE (Intel(R) HD Graphics Family)",
    "info": {
      "AzureCanvasBackend": "direct2d",
      "AzureFallbackCanvasBackend": "cairo",
      "AzureContentBackend": "direct2d"
    }
  },
  "javaScript": {
    "incrementalGCEnabled": true
  },
  "accessibility": {
    "isActive": false,
    "forceDisabled": 0
  },
  "libraryVersions": {
    "NSPR": {
      "minVersion": "4.9.5",
      "version": "4.9.5"
    },
    "NSS": {
      "minVersion": "3.14.3.0 Basic ECC",
      "version": "3.14.3.0 Basic ECC"
    },
    "NSSUTIL": {
      "minVersion": "3.14.3.0",
      "version": "3.14.3.0"
    },
    "NSSSSL": {
      "minVersion": "3.14.3.0 Basic ECC",
      "version": "3.14.3.0 Basic ECC"
    },
    "NSSSMIME": {
      "minVersion": "3.14.3.0 Basic ECC",
      "version": "3.14.3.0 Basic ECC"
    }
  },
  "userJS": {
    "exists": false
  },
  "extensions": [
    {
      "name": "Adblock Plus",
      "version": "2.2.3",
      "isActive": true,
      "id": "{d10d0bf8-f5b5-c8b4-a8b2-2b9879e08c5d}"
    },
    {
      "name": "Bookmark Favicon Changer",
      "version": "1.74",
      "isActive": true,
      "id": "bookmarkfaviconchanger@sonthakit"
    },
    {
      "name": "FireShot",
      "version": "0.98.31",
      "isActive": true,
      "id": "{0b457cAA-602d-484a-8fe7-c1d894a011ba}"
    },
    {
      "name": "Java Console",
      "version": "6.0.33",
      "isActive": true,
      "id": "{CAFEEFAC-0016-0000-0033-ABCDEFFEDCBA}"
    },
    {
      "name": "Java Console",
      "version": "6.0.37",
      "isActive": true,
      "id": "{CAFEEFAC-0016-0000-0037-ABCDEFFEDCBA}"
    },
    {
      "name": "One Click Popup Dictionary",
      "version": "1.2",
      "isActive": true,
      "id": "[e-mail]"
    },
    {
      "name": "Smartest Bookmarks Bar",
      "version": "1.11",
      "isActive": true,
      "id": "{b442f4c0-c292-4998-aabe-48608a73ba75}"
    },
    {
      "name": "Favicon Picker 2",
      "version": "0.6.2.15",
      "isActive": false,
      "id": "{446c03e0-2c35-11db-a98b-0800200c9a66}"
    },
    {
      "name": "Skype Click to Call",
      "version": "5.10.0.9560",
      "isActive": false,
      "id": "{82AF8DCA-6DE9-405D-BD5E-43525BDAD38A}"
    }
  ]
}


Actual results:

When the mouse is moved over the 'Go back one page button' on the navigation toolbar and is moved away again, the animation for the button fading is garbled. It remains garbled. This only appears if the button is enabled, i.e. you can go back a page on the current tab. Functionality is not affected.


Expected results:

Animation should be smooth and clearly defined.