Created attachment 73280 [details]
A document with a excel default border cell

Problem description: 
Conversion of Excel borders .xlsx is bad. Makes ugly documents.
The key problem is the default cell border width. Both Excel and LO use a think, 1 pixel border when a border is drawn using the native defaults on both platforms. 

However, a default border in a document created in Excel is not converted to a default LO border. Instead, a thicker border is created. So the formatting looks different. For documents where the borders is applied to a contiguous grid of cells, the converted document looks ugly. 


Steps to reproduce:
1. Create a native excel document, and apply the default borders to create a box border for the cell (all sides). Such a document is attaced. 
2. Import this document into LO. 
3. With the document open in LO, choose a blank cell and apply a box default border with LO. 

Current behavior:
After step 3, note how the border width just created is thin (1 px) and the imported Excel content has a much thicker border.

Expected behavior:
The default border width in Excel should convert to the default border with in LO. Therefore, there should be no visible difference between the two borders of step 3. They should both be as think as the border created in LO. 

              
Operating System: All
Version: 4.0.0.1 rc